NCERT-Biology Flashcards

Question

Ctenphora: sex? reproduction?

Answer 1

sexes not separate fertilisation is external only by sexual means indirect development

Answer 2

Ctenoplana

Answer 3

1. aka sea walnuts or comb jellies 2. eight external rows of ciliated comb plates, which help in locomotion 3. bioluminiscence

Answer 4

1. exclusively marine 2. tissue level organisation 3. diploblastic 4. radially symmetrical 5. acoelomata 6. commonly known as sea walnuts or comb jellies 7. body bears eight external rows of ciliated comb plates, which help in locomotion 8. digestion is both extracellular and intracellular 9. Bioluminiscence is well-marked 10. sexes are not separate 11. reproduction only by sexual means; fertilisation is external 12. wg. Pleurobrachia and Ctenoplana

Answer 5

mostly endoparasites found in animals including humans

Answer 6

organ level triploblastic

Answer 7

acoelomate

Answer 8

hooks and suckers some absorb nutrients from hosts' body through their body surface specialised cells, called flame cells help in osmo-regulation and excretion

Answer 9

sexes not separate **able to reproduce asexually and sexually, but sexual reproduction is preferable** fertilisation is internal development indirect

Answer 10

tapeworm liver fluke

Answer 11

dorsally flattened body, hence called flatworms some mebers like Planaria possess high regeneration capacity

Answer 12

1. mostly endoparasites; found in animals including human beings 2. organ level of organisation 3. triploblastic 4. bilaterally symmetrical 5. acoelomate 6. dorso-ventrally flattened body, hence called flatworms 7. hooks and suckers are present 8. specialised cells called flame cells for osmo-regulation and excretion 9. some members like planaria possesses high regeneration capacity 10. sexes are not separate 11. fertilisation is internal 12. eg. tapeworm and liver fluke

Answer 13

free-living, aquatic, terresterial as well as parasitic

Answer 14

organ-system level triploblastic

Answer 15

bilaterally

Answer 16

pseudocoelomate

Answer 17

well-developed muscular pharynx and an excretory tube that removes body waste from body cavity through excretory pore first phylum with complete digestive system

Answer 18

sexes separate **reproduction is usually sexual** fertilisation is internal development ma be direct or indirect

Answer 19

roundworm hookworm

Answer 20

often females are longer

Answer 21

1. may be freeliving, aquatic and terresterial or parasitic in plants and animals 2. organ-system level 3. triploblastic 4. bilaterally symmetrical 5. pseudocoelomate 6. well developed muscular pharynx as well as an excretory tube to remove body waste from body cavity through excretory pores 7. circular in cross-section, hence called roundworms 8. sexes are separate 9. fertilisation is internal 10. eg. roundworm, filaria worm and hookworm

Answer 22

aquatic or terresterial free-living or parasitic

Answer 23

organ system level triploblastic

Answer 24

1. Their body surface is distinctly marked out into segments or metameres 2. They possess longitudinal and circular muscles which help in locomotion 3. Aquatic annelids likeNereis possess lateral appendages, parapodia, which help in swimming. 4. A closed circulatory system is present, first phylum to have so 5. Nephridia help in osmoregulation and excretion 6. Neural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord

Answer 25

some like earthworms and leeches do not have separate sexes while nerets have separate sexes some reproduce both asexually (budding) as well as sexually while some like leeches reproduce only sexually

Answer 26

earthworms blood sucking leech

Answer 27

Arthropods are found in virtually every known **marine (ocean-based), freshwater, and terrestrial (land-based) ecosystem**

Answer 28

organ system level triploblastic

Answer 29

1. The body of arthropods is covered by chitinous exoskeleton. 2. The body consists of head, thorax and abdomen. 3. They have jointed appendages (arthros-joint, poda-appendages). 4. Respiratory organs are gills, book gills, book lungs or tracheal system. first phylum to have respiratory system present. 5. Circulatory system is of open type. 6. Sensory organs like antennae, eyes (compound and simple), statocysts or balancing organs are present. 7. Excretion takes place through malpighian tubules 8. segmentation is observed

Answer 30

mostly separate sexes Arthropods reproduce by sexual reproduction fertilisatio is internal mostly oviparous development may be direct or indirect

Answer 31

This is the largest phylum of Animalia which includes insects. Over two-thirds of all named species on earth are arthropods Economically important insects – Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect) Vectors – Anopheles, Culex and Aedes (Mosquitoes) Gregarious pest – Locusta (Locust) Living fossil – Limulus (King crab).

Answer 32

Molluscs are terrestrial or aquatic | (marine or fresh water)

Answer 33

organ system level triploblastic

Answer 34

1. Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and visceral hump. 2. A soft and spongy layer of skin forms a mantle over the visceral hump. 3. The space between the hump and the mantle is called the mantle cavity in which feather like gills are present. 4. They have respiratory and excretory functions. 5. The anterior head region has sensory tentacles. 6. The mouth contains a file-like rasping organ for feeding, called radula. 7. segmentation is absent

Answer 35

They are usually dioecious and oviparous with indirect development.

Answer 36

Apple snail, Pearl oyster, cuttlefish, squid, devil fish, chiton, tusk shell

Answer 37

All are marine animals

Answer 38

organ system level triploblastic

Answer 39

The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical

Answer 40

1. Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side. 2. The most distinctive feature of echinoderms is the presence of water vascular system which helps in locomotion, capture and transport of food and respiration. 3. An excretory system is absent. 4. segmentation is absent

Answer 41

1. Sexes are separate. 2. Reproduction is sexual. 3. Fertilisation is usually external. 4. Development is indirect with free-swimming larva

Answer 42

star fish, sea urchin, sea lily, sea cucumber and brittle star

Answer 43

marine animals

Answer 44

organ system level triploblastic

Answer 45

1. The body is cylindrical and is composed of an anterior proboscis, a collar and a long trunk 2. Circulatory system is of open type. Respiration takes place through gills. 3. Excretory organ is proboscis gland 4. Hemichordata was earlier considered as a sub-phylum under phylum Chordata. But now it is placed as a separate phylum under non-chordataHemichordates have a rudimentary structure in the collar region called stomochord, a structure similar to notochord. 5. segmentation is absent

Answer 46

Sexes are separate. Fertilisation is external. Development is indirect

Answer 47

Balanoglossus and Saccoglossus

Answer 48

They live in **marine, freshwater, terrestrial, and aerial habitats**.

Answer 49

organ system level triploblastic

Answer 50

1. All chordates possess 5 [synapomorphies](https://en.wikipedia.org/wiki/Apomorphy_and_synapomorphy), or primary characteristics, at some point during their larval or adulthood stages that distinguish them from all other taxa. These 5 synapomorphies include 1. a [notochord](https://en.wikipedia.org/wiki/Notochord), 2. [dorsal hollow nerve cord](https://en.wikipedia.org/wiki/Dorsal_nerve_cord), 3. [endostyle](https://en.wikipedia.org/wiki/Endostyle) or thyroid, 4. [pharyngeal slits](https://en.wikipedia.org/wiki/Pharyngeal_slit), and 5. a post-anal tail. 2. a closed circulatory system. 3. segmentation is present

Answer 51

usually separate sexes fertilisation internal

Answer 52

1. Urochordata 1. notochord is present only in larval tail 2. eg. ascidia, salpa 2. Cephalochordata 1. notochord extends from head to tail and is persistent throughout their life 2. eg. Lancelet the above two subphylas are referred to as protochordata and are exclusively marine 3. Vertebrata 1. possess notochord during embryoinc stage 2. replaced by a cartilaginous or bony vertebral column in adult 3. Besides the basic chordate characters, vertebrates have a ventral muscular heart with two, three or four chambers, kidneys for excretion and osmoregulation and paired appendages which may be fins or limbs.

Answer 53

1. Notochord: present in chordates 2. central nervous system 1. dorsal, hollow and single in chordata 2. ventral, solid and double in non-chordata 3. pharynx 1. perforated by gill slits in chordata 2. gill slits are absent in non-chordates 4. heart 1. ventral in chordata 2. dorsal in non chordata, if present at all 5. post anal tail 1. present in chordata

Answer 54

1. Plants 1. do not have differentiated body- Thyllophyta 2. have differentiated plant body 1. without specialised vascular tissue - Bryophyta 2. with vascular tissue 1. do not produce seeds- Pteridophyta 2. produce seeds- Phanerograms 1. Gymnosperms- naked seeds 2. Angiosperms- Seeds inside fruits 1. Monocotyledons 2. Dicotyledons

Answer 55

1. naked seeds (read: Gym mein naked hona padta hai) i.e. ovules are not enclosed by any ovary wall. The seeds that develop post-fertilisation are naked too. 2. usually **perennial, evergreen** and **woody** 3. Examples are **pines**, such as deodar; **giant redwood tree** **Seguoia** 4. medium-sized trees or tall trees and shrubs 5. roots are generally **tap roots.** Roots in some genera have fungal association in the form of **mycorrhiza (Pinus)**, while in some others **(Cgcas**) small specialised roots called coralloid roots are associated with N2-fixing cyanobacteria. 6. leaves in gymnosperms are well-adapted to withstand **extremes** of temperature, humidity and wind. In conifers, the needle-like leaves reduce the surface area. Their **thick cuticle** and **sunken stomata** also help to reduce water loss. 7. gymnosperms are **heterosporous**; they produce haploid microspores and megaspores. The two kinds of spores are produced within sporangia that are borne on sporophylls which are arranged spirally along an axis to form lax or compact **strobili or cones**.

Answer 56

* The seeds develop inside an organ which is modified to become a **fruit**. These are also called **flowering plants**. * the pollen grains and ovules are developed in specialised structures called **flowers**. * The male sex organ in a flower is the **stamen**. Each stamen consists of a slender filament with an anther at the tip. The anthers, following [Meiosis](https://www.pmfias.com/meiosis-meiotic-cell-division-mitosis-meiosis-comparison/), produce **pollen grains**. * The female sex organ in a flower is the **pistil** or the **carpel**. Pistil consists of an ovary enclosing one to many ovules. Within ovules are present highly reduced female gametophytes termed embryo-sacs. The embryo-sac formation is preceded by meiosis. Hence, each of the cells of an embryo-sac is **haploid**.Pollen grain, after dispersal from the anthers, are carried by wind or various other agencies to the stigma of a pistil. This is termed as **pollination**. * The pollen grains germinate on the stigma and the resulting pollen tubes grow through the tissues of stigma and style and reach the ovule. * The pollen tubes enter the embryo-sac where two male gametes are discharged. One of the male gametes fuses with the egg cell to form a **zygote (syngamy)**. * The other male gamete fuses with the diploid secondary nucleus to produce the **triploid primary endosperm nucleus (PEN).** * Because of the involvement of two fusions, this event is termed as **double fertilisation**, an event **unique to angiosperms**.The zygote develops into an embryo (with one or two cotyledons) and the PEN develops into endosperm which provides nourishment to the developing embryo. * The synergids and antipodals degenerate after fertilisation. During these events the ovules develop into seeds and the ovaries develop into fruit. * Plant embryos in seeds have structures called **cotyledons**. Cotyledons are called ‘**seed leaves**’ because in many instances they emerge and become green when the seed germinates. Thus, cotyledons represent a bit of pre-designed plant in the seed.

Answer 57

The nerve fibres of the PNS are of two types: 1. **afferent fibres → tissues/organs to brain**. 2. **efferent fibres → brain to tissues/organs**. * The afferent nerve fibres transmit impulses from tissues/organs to the CNS and the efferent fibres transmit regulatory impulses from the CNS to the concerned peripheral tissues/organs. * The PNS is divided into two divisions called **somatic neural system** and **autonomic neural system**. * The somatic neural system relays impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body. 1. **Somatic Neural System → Brain to Voluntary muscles**. 2. **Autonomic Neural System → Brain to Involuntary muscles**. * The autonomic neural system is further classified into **sympathetic neural system** and **parasympathetic neural system**.

Answer 58

CNS includes the **brain** and the **spinal cord** and is the site of information processing and control.

Answer 59

The brain is enclosed within the skull, which provides frontal, lateral and dorsal protection. **The skull consists of 22 bones, 14 of which form the facial bones and the remaining 8 form the cranial bones**. Anatomically, the brain is **contained within the cranium and is surrounded by the cerebrospinal fluid.** The Cerebrospinal Fluid (CSF) is a fluid that **circulates within the skull and spinal cord**, filling up hollow spaces on the surface of the brain. Every day, the **specialised ependymal cells produce around 500mL of cerebrospinal fluid.** The primary function of the CSF is to **act as a buffer for the brain, cushioning mechanical shocks and dampening minor jolts.** It also provides **basic immunological protection** to the brain. Furthermore, CSF provides **buoyancy** for the brain. i.e., the brain is suspended in a layer of CSF, wherein, the weight of the brain is nearly negated. If the brain is not suspended in CSF, it would be impeded by its weight, consequently cutting off the blood supply in the lower half of the brain. It would lead to the death of neurons in the affected area. * The human brain is well protected by the skull. Inside the skull, the brain is covered by **cranial meninges** consisting of an outer layer called **dura mater**, a very thin middle layer called **arachnoid** and an inner layer (which is in contact with the brain tissue) called **pia mater**.

Answer 60

1. **Grey matter** mainly consists of various types of cells, which make up the bulk of the brain. 2. **White matter** is primarily composed of axons, which connect various grey matter areas of the brain with each other.

Answer 61

1. Forebrain 2. Mid brain 3. hindbrain

Answer 62

It is the anterior part of the brain. The forebrain consists of **cerebrum, thalamus** and **Limbic system** (**hypothalamus)**. *Controls the reproductive functions, body temperature, emotions, hunger and sleep.*

Answer 63

Smallest and central part of the brain The *midbrain* consists of: * Tectum * Tegmentum The midbrain is located between the thalamus/hypothalamus of the forebrain and pons of the hindbrain. A canal called the **cerebral aqueduct** passess through the midbrain.

Answer 64

The lower part of the brain The *hindbrain* is composed of: * Cerebellum * Medulla * Pons ***Hindbrain functions:** The three regions of the hindbrain coordinates all processes necessary for survival. These induce breathing, heartbeat, sleep, wakefulness and motor learning.*

Answer 65

* the largest part of the brain. * It consists of the cerebral cortex (layer of cells which covers the cerebral hemisphere) and other subcortical structures. The cerebral cortex is referred to as the **grey matter** due to its greyish appearance. The neuron cell bodies are concentrated here giving the colour. * Fibres of the tracts are covered with the **myelin sheath**, which constitute the inner part of cerebral hemisphere. They give an opaque white appearance to the layer and, hence, is called the **white matter**. * It is composed of two cerebral hemispheres that are joined together by heavy, dense bands of fibre called the corpus callosum. * The cerebrum is further divided into four sections or lobes: * **Frontal lobe**: It is associated with parts of speech, planning, reasoning, problem-solving and movements. * **Parietal lobe**: Help in movements, the perception of stimuli and orientation. * **Occipital lobe**: It is related to visual processing. * **Temporal lobe**: This region is related to perception and recognition of memory, auditory stimuli and speech. * The exterior portion of the cerebrum is called the cortex or the cerebral mantle. The cortex is extremely convoluted, due to which, it has a large surface area. * The cerebrum also includes: * **Sensory areas**: To receive the messages. * **Association areas**: These areas integrate the incoming sensory information. It also forms a connection between sensory and motor areas. * **Motor areas**: This area is responsible for the action of the voluntary muscles.

Answer 66

The cerebrum is responsible for thinking, intelligence, consciousness and memory. It is also responsible for interpreting touch, hearing and vision.

Answer 67

The thalamus is a small structure, located right above the brain stem responsible for relaying sensory information from the [**sense organs**](https://byjus.com/biology/sense-organs/). It is also responsible for transmitting motor information for movement and coordination. Thalamus is found in the limbic system within the cerebrum. This limbic system is mainly responsible for the formation of new memories and storing past experiences.

Answer 68

located precisely below the thalamus. It is considered the primary region of the brain, as it is involved in the following functions: 1. Receives impulses 2. Regulates body temperature 3. Controls the mood and emotions 4. Controls the sense of taste and smell 5. Synthesises the body’s essential hormones 6. Coordinates the messages from the autonomous nervous system 7. Controls appetite, peristalsis, the rate of heartbeat, and blood pressure 8. Forms an axis with the pituitary gland which is the main link between the nervous and the endocrine systems

Answer 69

* The inner parts of cerebral hemispheres and a group of associated deep structures like amygdala, hippocampus, etc., form a complex structure called the **limbic lobe or limbic system**. Along with the hypothalamus, it is involved in the **regulation of sexual behaviour, expression of emotional reactions** (e.g., excitement, pleasure, rage and fear), and motivation.

Answer 70

The tectum is a small portion of the brain, specifically the dorsal part of the midbrain. It serves as a relay centre for the sensory information from the ears to the cerebrum. It also controls the reflex movements of the head, eye and neck muscles. It provides a passage for the different neurons moving in and out of the cerebrum.

Answer 71

Tegmentum is a region within the brainstem. It is a complex structure with various components, which is mainly involved in body movements, sleep, arousal, attention, and different necessary reflexes. It forms the platform for the midbrain and connects with the thalamus, cerebral cortex and the spinal cord.

Answer 72

the second largest part of the brain, located in the posterior portion of the medulla and pons. The cerebellum and cerebrum are separated by cerebellar tentorium and transverse fissure. Cortex is the outer surface of the cerebellum, and its parallel ridges are called the folia. Apart from this, the cerebellum has the cerebellar peduncles, cerebellar nuclei, anterior and posterior lobes. The cerebellum consists of two hemispheres, the outer grey cortex and the inner white medulla. The main functions of the cerebellum include: 1. It senses equilibrium. 2. Transfers information. 3. Coordinates eye movement. 4. It enables precision control of the voluntary body movements. 5. Predicts the future position of the body during a particular movement. 6. Both anterior and posterior lobes are concerned with the skeletal movements. 7. The cerebellum is also essential for making fine adjustments to motor actions. 8. Coordinates and maintains body balance and posture during walking, running, riding, swimming.

Answer 73

The medulla oblongata is a small structure present in the lowest region of the brain. It mainly controls the body’s autonomic functions such as heartbeat, breathing, and digestion. It **plays a primary role in connecting the spinal cord, pons and the cerebral cortex.** Also, it helps us in maintaining our posture and controlling our reflexes. * **Vomiting:** It is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomit centre in the **medulla**. A feeling of nausea precedes vomiting.

Answer 74

The pons is the primary structure of the brain stem present between the midbrain and medulla oblongata. It serves as a relay signals between the lower cerebellum, spinal cord, the midbrain, cerebrum and other higher parts of the brain. The main functions of the pons include: 1. Controlling sleep cycles. 2. Regulating the magnitude and frequency of the respiration. 3. Transfers information between the cerebellum and motor cortex. 4. Pons is also involved in sensations, such as the sense of taste, hearing and balance.

Answer 75

composed of three major parts, namely, cell body, dendrites and axon The cell body contains cytoplasm with typical cell organelles and certain granular bodies called Nissl’s granules There are two types of axons, namely, myelinated and nonmyelinated. The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. Myelinated nerve fibres are found in spinal and cranial nerves. Unmyelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon, and is commonly found in autonomous and the somatic neural systems

Answer 76

1. Hypothalamus 2. Pituitary 3. Pineal 4. Thyroid and Parathyroid 5. Thymus 6. Pancreas 7. Adrenal 8. Testes and Ovary

Answer 77

* These hormones **regulate the synthesis and secretion of pituitary hormones**. However, the hormones produced by hypothalamus are of two types, the **releasing hormones** (which stimulate secretion of pituitary hormones) and the **inhibiting hormones** (which inhibit secretions of pituitary hormones). * For example a hypothalamic hormone called **Gonadotrophin** releasing hormone (GnRH) stimulates the pituitary synthesis and release of gonadotrophins. On the other hand, **somatostatin** from the hypothalamus inhibits the release of growth hormone from the pituitary. * These hormones originating in the hypothalamic neurons, pass through axons and are released from their nerve endings. These hormones reach the pituitary gland through a portal circulatory system and regulate the functions of the anterior pituitary. The posterior pituitary is under the direct neural regulation of the hypothalamus.

Answer 78

* located in a bony cavity called **sella tursica** and is attached to hypothalamus by a stalk. * Consists of three parts * Pars distallis also called anterior pituitary * Pars intermedia: in humans, the pars intermedia is **almost merged** with pars distalis. * Pars nervosa also called posterior pituitary * Pars distallis and Pars intermedia form adenohypophysis while pars nervosa is called neurohypophysis * Pars distallis produces * Growth Hormone (GH): Over-secretion of GH stimulates abnormal growth of the body leading to gigantism and low secretion of GH results in stunted growth resulting in **pituitary dwarfism**. * Prolactin: regulates the growth of the **mammary glands** and **formation of milk** in them * Thyroid stimulating Hormone (TSH): stimulates the synthesis and secretion of **thyroid hormones** from the thyroid gland. * ACTH: stimulates the synthesis and secretion of **steroid hormones** from adrenal cortex * LH and FSH: stimulate **gonadal activity** and hence are called **gonadotrophins**. Spermatogenesis in males and ovulation in females * Pars intermedia secretes only MSH: MSH acts on the **melanocytes (melanin containing cells)** and **regulates pigmentation of the skin.** * **Pars nervosa:** stores and releases two hormones called **oxytocin** and **vasopressin**, which are actually synthesised by the **hypothalamus** and are transported axonally to neurohypophysis. * Oxytocin acts on the **smooth muscles** of our body and stimulates their contraction. In females, it stimulates a vigorous contraction of uterus at the time of **child birth**, and **milk ejection** from the mammary gland. * Vasopressin acts mainly at the kidney and **stimulates resorption of water** **and electrolytes** by the distal tubules and thereby reduces loss of water through urine (**diuresis**). Hence, it is also called as **Anti-Diuretic Hormone (ADH).**

Answer 79

1. located on the dorsal side of forebrain. 2. secretes a hormone called **melatonin** 3. **melatonin plays a role in** 1. **diurnal rhythm** 2. **body temp** 3. **metabolism** 4. **pigmentation** 5. **menstrual cycle**

Answer 80

1. composed of two lobes which are located on either side of the **trachea**. Both the lobes are interconnected with a thin flap of connective tissue called **isthmus**. 2. Two hormones 1. T3 2. T4 aka Thyroxine 3. also secretes a protein hormone called **Thyrocalcitonin (TCT)** which regulates the **blood calcium levels**. * **Iodine** is essential for the normal rate of hormone synthesis in the thyroid. Deficiency of iodine in our diet results in **hypothyroidism** and enlargement of the thyroid gland, commonly called **goitre**.Hypothyroidism during pregnancy causes **defective development** and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc. In adult women, hypothyroidism may cause menstrual cycle to become irregular. * Thyroid hormones play an important role in * basal metabolic rate * RBC formation * contols metabolsim of carbohydrates, proteins, fats * maintenance of electrolyte and water balance

Answer 81

1. four parathyroid glands are present on the back side of the thyroid gland, one pair each in the two lobes of the thyroid gland. 2. secrete a peptide hormone called **Parathyroid Hormone (PTH)**. The secretion of PTH is regulated by the circulating levels of calcium ions. Parathyroid hormone (PTH) **increases the Ca2+ levels in the blood**. 3. PTH is a **Hypercalcemic Hormone**, i.e., it increases the blood Ca2+ levels. PTH acts on bones and stimulates the process of **bone resorption** (dissolution/ demineralisation). Along with TCT, it plays a significant role in calcium balance in the body.

Answer 82

1. lobular structure located between lungs behind sternum 2. secretes the peptide hormones called **Thymosins**. that plays a major role in the development of the **immune system** * Thymosins play a major role in the differentiation of **T-lymphocytes**, which provide cell-mediated immunity. * In addition, thymosins also promote production of **antibodies** to provide humoral immunity. * Thymus is degenerated in old individuals resulting in a decreased production of thymosins. As a result, the immune responses of old persons become weak.

Answer 83

1. one pair of adrenal glands, one at the anterior part of each kidney. The gland is composed of two types of tissues. The centrally located tissue is called the **adrenal medulla**, and outside this lies the **adrenal cortex**. 2. Adrenal Medulla secretes two hormones, called catecholamines * adrenaline (aka epinephrine) * noradrenaline * Adrenaline and noradrenaline are rapidly secreted in response to **stress** of any kind and during emergency situations and are called **emergency hormones** or **hormones of Fight or Flight**. These hormones increase alertness, pupilary dilation, piloerection (raising of hairs), sweating etc. * Catecholamines also stimulate the breakdown of glycogen resulting in an **increased concentration of glucose in blood**. In addition, they also stimulate the breakdown of lipids and proteins. 3. The adrenal cortex secretes many hormones, commonly called as **corticoids**. The corticoids, which are involved in carbohydrate metabolism are called glucocorticoids. In our body, **cortisol** is the main glucocorticoid. Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids. **Aldosterone** is the main mineralocorticoid in our body. * Cortisol is also involved in maintaining the cardio-vascular system as well as the kidney functions. * Glucocorticoids, particularly cortisol, produces anti-inflammatory reactions and suppresses the immune response. * Cortisol stimulates the RBC production. * Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of Na+ and water and excretion of K+ and phosphate ions. Thus, aldosterone helps in the maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure. * Small amounts of androgenic steroids are also secreted by the adrenal cortex which play a role in the growth of axial hair, pubic hair and facial hair during puberty.

Answer 84

* Pancreas is a **composite gland** which acts as **both exocrine and endocrine gland**. * The endocrine pancreas consists of ‘**Islets of Langerhans**’. There are about 1 to 2 million Islets of Langerhans in a normal human pancreas representing only 1 to 2 per cent of the pancreatic tissue. * The two main types of cells in the Islet of Langerhans are called a-cells and p-cells. The a-cells secrete a hormone called **glucagon**, while the p-cells secrete **INSULIN**. * Glucagon is a peptide hormone, and plays an important role in maintaining the normal **blood glucose levels**. Glucagon acts mainly on the **liver cells (hepatocytes)** and stimulates **glycogenolysis** resulting in an increased blood sugar **(hyperglycemia)**. * Insulin is a peptide hormone, which plays a major role in the regulation of **glucose** [**homeostasis**](https://www.pmfias.com/ecological-succession-primary-secondary-succession-homeostasis/). Insulin acts mainly on **hepatocytes** and **adipocytes** (cells of adipose tissue), and **enhances cellular glucose uptake and utilisation**. As a result, there is a rapid movement of glucose from blood to hepatocytes and adipocytes resulting in decreased blood glucose levels **(hypoglycemia)**. * The **glucose** [**homeostasis**](https://www.pmfias.com/ecological-succession-primary-secondary-succession-homeostasis/) in blood is thus maintained jointly by the two – insulin and glucagons. * Prolonged hyperglycemia leads to a complex disorder called **diabetes mellitus** which is associated with loss of glucose through urine and formation of harmful compounds known as **ketone bodies**. Diabetic patients are successfully treated with insulin therapy.

Answer 85

1. Testis performs dual functions as a **primary sex organ** as well as an **endocrine gland**. 2. produces group of hormones called **androgens** mainly **testosterone**. * Androgens regulate the development, maturation and functions of the **male accessory sex organs** like epididymis, vas deferens, seminal vesicles, prostate gland, urethra etc. * These hormones stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice etc. * Androgens play a major stimulatory role in the process of **spermatogenesis** (formation of spermatozoa). * Androgens act on the central neural system and influence the **male sexual behavior (libido)**. * These hormones produce anabolic (synthetic) effects on protein and carbohydrate metabolism.

Answer 86

1. produces two groups of steroid hormones called estrogen and progesterone. The **estrogen** is synthesized and secreted mainly by the growing ovarian follicles. After ovulation, the ruptured follicle is converted to a structure called corpus luteum, which secretes mainly **progesterone**. * Estrogens produce wide ranging actions such as stimulation of growth and activities of **female secondary sex organs**, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development. Estrogens also regulate **female sexual behavior**. * **Progesterone** supports pregnancy. Progesterone also acts on the mammary glands and stimulates the formation of **alveoli** (sac-like structures which store milk) and milk secretion.

Answer 87

* hormones are also secreted by some tissues which are not endocrine glands. * For example, the atrial wall of our heart secretes a very important peptide hormone called **Atrial Natriuretic Factor (ANF)**, which **decreases blood pressure**. When blood pressure is increased, ANF is secreted which causes dilation of the blood vessels. This reduces the blood pressure. * The **juxtaglomerular cells** of kidney produce a peptide hormone called **erythropoietin** which stimulates **Erythropoiesis (formation of RBC)**. * Endocrine cells present in different parts of the gastro-intestinal tract secrete four major peptide hormones, namely **Gastrin, Secretin, Cholecystokinin (CCK)** and **Gastric Inhibitory Peptide (GIP)**. * Gastrin acts on the gastric glands and stimulates the secretion of **hydrochloric acid** and **pepsinogen**. * Secretin acts on the exocrine pancreas and stimulates secretion of **water and bicarbonate ions.** * CCK acts on both pancreas and gall bladder and stimulates the secretion of **pancreatic enzymes and bile juice**, respectively. * GIP **inhibits gastric secretion** and motility.

Answer 88

1. The process of taking food into the body is called **ingestion**. 2. Teeth 1. Majority of mammals including human being forms two sets of teeth during their life 2. Arrangement of teeth in each half of the upper and lower jaw in the order I, C, PM, M is represented by a dental formula which in human is 2123/2123 [2-I,1-C,2-PM,3-M] 3. Our mouth has the **salivary glands** which secrete saliva. The saliva breaks down the **_starch into sugars_**. The saliva secreted into the oral cavity contains **electrolytes (Na+, K+, Cl”, HCOs)** and enzymes, **SALIVARY AMYLASE** and **LYSOZYME**. The chemical process of digestion is initiated in the oral cavity by the hydrolytic action of the carbohydrate splitting enzyme, the **salivary amylase**. About 30 per cent of starch is **hydrolysed** here by this enzyme (optimum pH 6.8) into a disaccharide – **maltose**. **Lysozyme** present in saliva acts as an **antibacterial** agent that prevents infections. 4. The tongue is attached to the floor of the oral cavity by the **frenulum** (a fold of skin beneath the tongue). The upper surface of the tongue has small projections called **papillae**, some of which bear taste buds.

Answer 89

1. oral cavity leads into a short **pharynx** which serves as a common passage for food and air. The esophagus and the trachea (wind pipe) open into the pharynx * A cartilaginous flap called **epiglottis** prevents the entry of food into the glottis during swallowing. [Glottis == opening of the wind pipe]. * Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus. The bolus is then conveyed into the pharynx and then into the oesophagus by swallowing or **deglutition**. * The bolus further passes down through the oesophagus by successive waves of muscular contractions called **peristalsis**. The **gastro-oesophageal sphincter** controls the passage of food into the stomach.

Answer 90

* inner lining of the stomach secretes **mucous, hydrochloric acid** and **digestive juices**. 1. *The mucous protects the lining of the stomach. mucous is produced by epithelial cells in the outer layer* 2. *The acid kills many **bacteria** that enter along with the food and makes the medium in the stomach **acidic**. The layer inside the epithelial layer is called oxyntic layer, that produces hydro chloric acid* 3. *The digestive juices break down the **proteins** into simpler substances.* * The stomach, located in the upper left portion of the abdominal cavity, has three major parts – a cardiac portion into which the oesophagus opens, a **fundic region** and a **pyloric portion** which opens into the first part of small intestine. * The stomach stores the food for 4-5 hours. The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and is called the **chyme**. * gastric glands produce two enzymes- pepsin and renin. Both help in protein digestion. Renin helps in digesting Caseinogen, protein in milk. * The *proenzyme [inactive precursor of an enzyme]* pepsinogen, on exposure to hydrochloric acid gets converted into the active enzyme **PEPSIN**, the *proteolytic (breakdown of proteins or peptides into amino acids)* enzyme of the stomach. * Pepsin converts **_proteins into proteoses and peptones_** (peptides). * The mucus and **bicarbonates** present in the gastric juice play an important role in **lubrication** and **protection** of the mucosal epithelium from excoriation by the highly concentrated hydrochloric acid. HCl provides the **acidic** pH (pH 1.8) **optimal for pepsins.** * **Rennin** is a proteolytic enzyme found in gastric juice of infants which helps in the **_digestion of milk proteins_.**

Answer 91

* distinguishable into three regions, a **‘C’ shaped duodenum**, a **long coiled middle portion jejunum** and a **highly coiled ileum**. * The opening of the stomach into the duodenum is guarded by the **pyloric sphincter**. Ileum opens into the large intestine. * The small intestine is highly coiled and is about **5 meters long**. It receives secretions from the liver and the pancreas. Besides, its wall also secretes juices. * these enzymes and secretions are received in the duodenum. The breakdown of biomacromolecules like proteins into dipeptides or amino acids or fats into fatty acids, occurs in the **duodenum** region of the small intestine. The simple substances thus formed are absorbed in the jejunum and ileum regions of the small intestine. * The secretions of the mucosa along with the bicarbonates from the pancreas protects the intestinal mucosa from **acid** as well as provide an **alkaline medium (pH 7.8)** for enzymatic activities. * The digested food passes into the blood vessels in the wall of the intestine. This process is called **absorption**. * The inner walls of the small intestine have thousands of finger-like outgrowths. These are called **villi (singular villus)**. The villi **increase the surface area for absorption** of the digested food. * Villi are supplied with a network of capillaries and a **large lymph** (a colourless fluid containing white blood cells) vessel called the **lacteal**. * The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This is called **assimilation**. * The food that remains undigested and unabsorbed then enters into the large intestine.

Answer 92

* The large intestine is wider and shorter than small intestine. It is about 1.5 metre in length. Its function is to absorb water and some salts from the undigested food material. * The remaining waste passes into the rectum and remains there as semi-solid faeces. The faecal matter is removed through the anus from time-to-time. This is called **egestion**. * It consists of **caecum**, **colon** and **rectum**. Caecum is a small blind sac which hosts some **symbiotic micro-organisms**. * A narrow finger -like tubular projection, the vermiform **appendix** which is a vestigial organ [small remnant of something that was once more noticeable], arises from the caecum. * The caecum opens into the colon. The colon is divided into three parts – an ascending, a transverse and a descending part. The descending part opens into the rectum which opens out through the anus. * No significant digestive activity occurs in the large intestine. The functions of large intestine are: absorption of some water, minerals and certain drugs; secretion of mucus which helps in adhering the waste (undigested) particles together and lubricating it for an easy passage. * The undigested, unabsorbed substances called faeces enters into the caecum of the large intestine through **ileo-caecal** valve, which prevents the back flow of the faecal matter. It is temporarily stored in the rectum till defaecation.

Answer 93

* wall of alimentary canal from oesophagus to rectum possesses four layers namely **serosa, muscularis, sub-mucosa** and **mucosa**. 1. Serosa is the outermost layer and is made up of a thin **mesothelium (epithelium of visceral organs)** with some connective tissues. 2. Muscularis is formed by **smooth muscles**. 3. The submucosal layer is formed of **loose connective tissues** containing nerves, blood and lymph vessels. In duodenum, glands are also present in sub-mucosa. * The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (**rugae**) in the stomach and small finger-like foldings called **villi** in the small intestine. **Mucosal epithelium** has **goblet cells** which secrete mucus that help in **lubrication**. Mucosa also forms glands in the stomach (**gastric glands**).

Answer 94

1. Salivary glands 2. Liver 3. Pancreas

Answer 95

* Saliva is mainly produced by three pairs of salivary glands, the parotids (cheek), the sub-maxillary (lower jaw) and the sub-linguals (below the tongue). * These glands situated just outside the buccal cavity secrete salivary juice into the buccal cavity. * The saliva breaks down the **_starch into sugars_**.

Answer 96

* The liver is a reddish brown gland situated in the upper part of the abdomen on the right side. * It is the **largest gland** in the body. * It secretes **bile juice** that is stored in a sac called the **gall bladder**. * The bile plays an important role in the **_digestion of fats_**. * It has two lobes. The hepatic lobules are the structural and functional units of liver containing **hepatic cells**. * The bile secreted by the hepatic cells passes through the hepatic ducts and is stored and concentrated in a thin muscular sac called the **gall bladder.** * The duct of **gall bladder (cystic duct)** along with the **hepatic duct from the liver**, forms the common **bile duct**. * The bile duct and the pancreatic duct open together into the duodenum as the common **hepato-pancreatic duct** which is guarded by a sphincter called the **sphincter of Oddi**.

Answer 97

* The pancreas is a large cream coloured gland located just below the stomach. * The pancreatic juice acts on **_carbohydrates and proteins_** and changes them into simpler forms. * The partly digested food now reaches the lower part of the small intestine where the intestinal juice [succus entericus] completes the digestion of all components of the food. * The pancreas is a compound (both **exocrine and endocrine**) elongated organ situated between the limbs of the ‘U’ shaped duodenum. * The exocrine portion secretes an **alkaline pancreatic juice** containing enzymes and the endocrine portion secretes **hormones, insulin and glucagon**. * contains amylase (breaks down carbohydrates), lypase (breaks down fats) and trypsin (breaks down proteins); thus pancreatic juice is called complete digestive juice

Answer 98

* The pancreatic juice contains inactive enzymes – trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases and nucleases. * Trypsinogen is activated by an enzyme, **enterokinase**, secreted by the intestinal mucosa into active **TRYPSIN**, which in turn **activates the other enzymes** in the pancreatic juice. * these enzymes help convert protein, peptones and proteoses into dipeptides * lipase breaks down fats into di and monoglycerides and further into fatty acids and glycerol * The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol and phospholipids but no enzymes. * Bile helps in **_emulsification of fats_**, i.e., breaking down of the fats into very small micelles. Bile also activates **LIPASES**. Small amounts of **lipases** are secreted by gastric glands.

Answer 99

* Most of the vitamins cannot be synthesized in our body but plants can synthesize almost all of them, so they are considered as **essential food factors**. However, the **bacteria of the gut** can produce some of the vitamins required by us. * The term “Vitamine” was coined from the word vital + amine since the earlier identified compounds had amino groups. Later work showed that most of them did not contain amino groups, so the letter ‘e’ was dropped and the term vitamin is used these days.

Answer 100

1. Vitamin A 2. Vitamin B1 aka Thiamine 3. Vitamin B2 aka Riboflavin 4. Vitamin B3 aka niacin 5. Vitamin B5 aka Pantothenic acid 6. Vitamin B6 aka pyridoxine 7. Vitamin B7 aka Biotin 8. Vitamin B9 aka Folic acid 9. Vitamin B12 10. Vitamin C aka ascorbic acid 11. Vitamin D 12. Vitamin E 13. Vitamin K

Answer 101

* Fat-soluble vitamins are stored in the body's liver, fatty tissue, and muscles. * The four fat-soluble vitamins are vitamins A, D, E, and K. These vitamins are absorbed more easily by the body in the presence of dietary fat.

Answer 102

* Water-soluble vitamins are **not stored in the body**. * The nine water-soluble vitamins are **vitamin C and all the B vitamins**. * Any leftover or excess amounts of these leave the body through the urine. * They have to be consumed on a regular basis to prevent shortages or deficiencies in the body. The **exception to this is vitamin B12, which can be stored in the liver for many years.**

Answer 103

form and maintain healthy teeth, bones, soft tissue, mucous membranes, and skin. deficiency can cause night-blindness Found in Cod-[liver](https://www.webmd.com/digestive-disorders/picture-of-the-liver) oil, milk, eggs, sweet potatoes, carrots, leafy vegetables

Answer 104

* [Thiamine](https://medlineplus.gov/ency/article/002401.htm) (vitamin B1) helps the body cells change [carbohydrates](https://medlineplus.gov/ency/article/002469.htm) into energy. Getting enough carbohydrates is very important during pregnancy and breastfeeding. It is also essential for heart function and healthy nerve cells. * deficiency can cause Beri-Beri. There are two major types of Beriberi: wet Beriberi which affects the cardiovascular system and dry Beriberi which affects the nervous system. People with wet Beriberi may experience increased heart rate, shortness of breath, and swelling of the lower legs. Signs and symptoms of dry Beriberi include difficulty walking; loss of feeling in the hands and/or feet; paralysis of the lower legs; mental confusion; speech difficulty; pain; and/or vomiting. Found in Beans and enriched, fortified, or whole-grain products such as bread, pasta, and cereals

Answer 105

* [Riboflavin](https://medlineplus.gov/ency/article/002411.htm) (vitamin B2) works with the other B vitamins. It is important for body growth and the production of red blood cells. * Deficiency can cause Ariboflavinosis (literally deficiency of riboflavin) * Found in whole grains, enriched grains and dairy products

Answer 106

* [Niacin](https://medlineplus.gov/ency/article/002409.htm) is a B vitamin that helps maintain healthy skin and nerves. It also has cholesterol-lowering effects at higher doses. * deficiency can cause pellagra (“3 Ds”: **diarrhea, dermatitis, and dementia**) * Found in mushrooms, fish, poultry, and whole grains

Answer 107

* [Pantothenic acid](https://medlineplus.gov/ency/article/002410.htm) (vitamin B5) is essential for the metabolism of food. It also plays a role in the production of hormones and cholesterol. * deficiency can cause paresthesia (**burning or prickling sensation that is usually felt in the hands, arms, legs, or feet**) * Found in chicken, broccoli, legumes and whole grains.

Answer 108

Vitamin B6 helps form red blood cells and maintain brain function. This vitamin also plays an important role in the proteins that are part of many chemical reactions in the body. The more [protein](https://medlineplus.gov/ency/article/002467.htm) you eat the more pyridoxine your body requires. deficiency can cause anemia Found in fortified cereals and soy products, eggs, peas, and spinach

Answer 109

* [Biotin](https://medlineplus.gov/ency/article/002410.htm) is essential for the metabolism of proteins and carbohydrates, and in the production of hormones and cholesterol. * deficiency can cause dermatitis * Found in many fruits and meat

Answer 110

* [Folate](https://medlineplus.gov/ency/article/002408.htm) works with vitamin B12 to help form red blood cells. It is needed for the production of DNA, which controls tissue growth and cell function. Any woman who is pregnant should be sure to get enough folate. Low levels of folate are linked to birth defects such as [spina bifida](https://medlineplus.gov/ency/article/001558.htm). Many foods are now fortified with folate in the form of folic acid. * deficiency can cause megaloblastic anemia * Found in leafy vegetables, lima, lentil, [kidney](https://www.webmd.com/kidney-stones/picture-of-the-kidneys), and garbanzo beans

Answer 111

important for metabolism. It also helps form red blood cells and maintain the [central nervous system](https://medlineplus.gov/ency/article/002311.htm). Found in fish, poultry, meat and dairy products.

Answer 112

is an antioxidant that promotes healthy teeth and gums. helps make collagen. It helps the body absorb iron and maintain healthy tissue. It is also essential for wound healing. found in Citrus fruits, berries, tomatoes, potatoes, broccoli, cauliflower, Brussels sprouts, red and green bell peppers, cabbage, and spinach

Answer 113

also known as the "sunshine vitamin," since it is made by the body after being in the sun. Ten to 15 minutes of sunshine 3 times a week is enough to produce the body's requirement of vitamin D for most people at most latitudes. People who do not live in sunny places may not make enough vitamin D. It is very hard to get enough vitamin D from food sources alone. Vitamin D helps the body absorb calcium. You need calcium for the normal development and maintenance of healthy teeth and bones. It also helps maintain proper blood levels of [calcium](https://medlineplus.gov/ency/article/002412.htm) and [phosphorus](https://medlineplus.gov/ency/article/002424.htm). Found in fortified milk and other dairy products, egg yolks; salmon, [cod liver oil](https://www.webmd.com/vitamins-supplements/ingredientmono-1040-cod+liver+oil.aspx?activeingredientid=1040&activeingredientname=cod+liver+oil)

Answer 114

is an antioxidant also known as tocopherol. It helps the body form red blood cells and use vitamin K. also, Without vitamin E, your body would have difficulty absorbing and storing vitamin A. Found in fortified cereals, leafy green vegetables, seeds, and nuts. and vegetable oils like sunflower, canola, and soybean

Answer 115

coagulation of blood Found in dark green leafy vegetables and in turnip or beet green. and fruits such as avocado. kiwi, and grapes

Answer 116

* These are inorganic nutrients that also play a key role in ensuring the health and well * They include the trace elements **copper, iodine, iron, manganese, selenium, and zinc** together with the macro elements **calcium, magnesium, potassium, and sodium**. * **Magnesium is essential for bone and teeth structure**. Low intake and blood levels of magnesium are associated with several conditions, including type 2 diabetes, metabolic syndrome, heart disease, and osteoporosis

Answer 117

Vit A Vit B9 i.e. Folic acid Iodine Iron Zinc

Answer 118

* A→ Night blindness * B1→ Beri-Beri * B2→ Retarded growth, bad skin * B12→ Anaemia * C→ Scurvy * D→ Rickets * K→ excessive bleeding * Calcium→ brittle bones, excessive bleeding * P→ bad teeth and bones * Fe→ Anaemia * I→goitre * Cu→ low appetite, retarded growth

Answer 119

* Fat is a major source of energy & **helps your body absorb vitamins**. * Fat has the **most calories** compared to any other nutrient. * Fats, also known as **triglycerides**, are **esters** of **three fatty acid chains** & the **alcohol glycerol**. i.e. * CH2OH-CHOH-CH2OH + 3 (R-COOH) =\> CH2COOR- CHCOOR-CH2COOR * Fats are solids at room temperature. Oil refers to a **fat with unsaturated fatty acid chains** that is liquid at room temperature * Fats, like other **lipids**, are generally **insoluble in water**.

Answer 120

* A lipid is chemically defined as a substance that is **insoluble in water** and soluble in alcohol and chloroform. * Lipids are an important component of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells. * **Cholesterol** and **triglycerides (fats)** are lipids. *

Answer 121

1. saturated 1. a fat in which the fatty acids all have **single bonds**. 2. A saturated fat has the **maximum number of hydrogens bonded to the carbons**, & therefore is **‘saturated’ with hydrogen atoms**. 3. **Most animal fats are saturated** whereas the **fats of plants & fish are generally unsaturated**. 4. Many experts recommend a **diet low in saturated fat**. 5. Saturated fats are popular with manufacturers of processed foods because they are **less vulnerable to rancidity** & are, in general, **more solid at room temperature** than unsaturated fats. 2. unsaturated * An unsaturated fat is a fatty acid in which there is **at least one double bond** within the fatty acid chain. * In cellular metabolism, unsaturated fat molecules contain **somewhat less energy** (i.e., fewer calories) than an equivalent amount of saturated fat. * The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more vulnerable it is to **rancidity** * **Antioxidants** can protect unsaturated fat from lipid oxidation.

Answer 122

* main types of “healthy” fats are: * **monounsaturated (single double bond),** * **polyunsaturated (more than one double bond),** * **alpha-linolenic acid (an omega-3 fatty acid)** and * **linoleic acid (an omega-6 fatty acid)**. * **Omega-3 and Omega-6 fatty acids** are **heart-healthy fats**. * They are both polyunsaturated. The difference is in where the first of the double bonds occurs. * Both omega-3 (ω-3) and omega-6 (ω-6) fatty acids are important components of cell membranes. * They are found in fish, soybean products, Walnuts, etc. * Both of these fatty acids are needed for growth and repair but can also be used to make other fatty acids * There is increasing support for omega-3 fatty acids in protecting against fatal heart disease and it is known that they have **anti-inflammatory effects**. There is also growing interest in the role of **omega-3 fatty acids in the prevention of diabetes** and certain types of cancer. * Some sources of these fats include almonds, cashews, pecans, peanuts, pine nuts, pumpkin, sesame seeds, sunflower seeds, Olive oil and olives, vegetable oils

Answer 123

* main types of **“unhealthy” fats** are **saturated & trans fat**. * Saturated fats are primarily found in foods that come from **animals, such as meat & dairy**. * Saturated fats are **unhealthy** because **they increase LDL (“bad” cholesterol) levels** in your body * Many saturated fats are **“solid” fats** that you can see, such as the fat in meat * Other sources of saturated fats include high-fat cheese, butter, Ice cream, palm & coconut oils, etc * **Trans fats or trans-unsaturated fatty acids** are a type of **unsaturated fats** that are **uncommon in nature**. * **Trans fats are worse than saturated fats**. * Trans fat is simply **liquid oils turned into solid fats** during **food processing**. * **Natural trans fats**, present in very small amounts in certain animal products, are **not considered harmful**. * But industrially produced artificial trans fats (**manufactured by adding hydrogen to vegetable oil**) have the tendency to negatively alter the **lipoprotein cholesterol profile** by **increasing the level of** **bad cholesterol (LDL)** while **decreasing the level of** **HDL or good cholesterol**. * These changes in the lipoprotein cholesterol clog arteries & cause hypertension, increase the risk of type-II diabetes, heart attacks & other cardiovascular diseases. * Foods containing trans fat are usually labelled as “**partially hydrogenated**”. * Partially hydrogenated oil is less likely to spoil, so foods made with it have a **longer shelf life**. * Trans fats are **easy to use, inexpensive to produce & last a long time**. * These trans fats are largely found in **vanaspati oil, margarine, bakery items, & in baked & fried foods**. * Even when the fat/oil contains less than 2% trans fat, **repeated heating can increase the trans fat content**.

Answer 124

India * Over 77,000 deaths annually are attributed to trans fats consumption in India. * **Feb 2021:** FSSAI has put a cap on **trans fatty acids (TFAs)** in food products, oils & fats. * FSSAI had capped **trans fats in oils & fats** to **3% by 2021**, & **2% by 2022** from the **current levels of 5%**. * From 01/01/2022, India will limit **trans fat to 2% by mass of the total oils/fats present in a food product**. * While FSSAI mentions edible oils & fats, it also applies to emulsions such as **margarine**. global * WHO has called for the elimination of **industrially-produced trans-fatty acids** **from the global food supply by** **2023**. (India will be achieving the target a year in advance) * **Denmark** became the first country to limit industrially produced trans fats in all foods to 2% of fats & oils. * EU adopted a new regulation to limit industrially produced trans fat to 2% in foods sold within the EU. * It is now well known that **trans fat can be completely eliminated & replaced with healthier substitutes without any change in the food taste or cost**.

Answer 125

* Cells of the human body exhibit three main types of movements, namely, **amoeboid, ciliary** and **muscular**. * Some specialized cells in our body like **macrophages** and **leucocytes** in blood exhibit amoeboid movement. It is effected by **pseudopodia** formed by the streaming of protoplasm (as in Amoeba). * Ciliary movement occurs in most of our internal tubular organs which are lined by **ciliated epithelium**. The coordinated movements of cilia in the **trachea** help us in removing dust particles and some of the foreign substances inhaled along with the atmospheric air. Passage of **ova** through the female reproductive tract is also facilitated by the ciliary movement. * Movement of our limbs, jaws, tongue, etc. require muscular movement. The contractile property of muscles are effectively used for locomotion and other movements by human beings and majority of multicellular organisms.

Answer 126

* Muscle is a specialized tissue of mesodermal origin. [**Mesodermal** == the middle layer of cells or tissues of an embryo, or the parts derived from this (e.g. cartilage, muscles, and bone)] * About 40-50 per cent of the body weight of a human adult is contributed by muscles. * Based on their location, three types of muscles are identified : (i) Skeletal (ii) Visceral [the internal organs in the main cavities of the body] and (iii) Cardiac.

Answer 127

* closely associated with the skeletal components of the body. * They have a striped appearance under the microscope and hence are called **striated muscles**. * As their activities are under the voluntary control of the nervous system, they are known as **voluntary muscles** They are primarily involved in locomotory actions and changes of body postures. * Each organized skeletal muscle in our body is made of a number of **muscle bundles or fascicles** held together by a common connective tissue layer called **fascia**. * Each muscle bundle contains a number of muscle fibres. Each muscle fibre is lined by the plasma membrane called **sarcolemma** enclosing the sarcoplasm. * The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of **calcium ions**. * A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called **myofilaments or myofibrils**. * Each myofibril has alternate dark and light bands on it. The striated appearance is due to the distribution pattern of two important proteins – **Actin** and **Myosin**. * Actin and myosin are polymerized proteins with contractility. A motor neuron carries signal to the muscle fibre which generates an action potential in it. This causes the release of Ca++ from sarcoplasmic reticulum. * **Ca++** activates actin which binds to the myosin head to form a cross bridge. These cross bridges pull the actin filaments causing them to slide over the myosin filaments and thereby causing contraction. Ca++ are then returned to sarcoplasmic reticulum which inactivate the actin. Cross bridges are broken and the muscles relax. * Muscles are classified as Red and White fibres based primarily on the amount of **red coloured myoglobin** pigment in them.

Answer 128

* Visceral muscles are located in the inner walls of hollow visceral organs of the body like the alimentary canal, reproductive tract, etc. * They do not exhibit any striation and are smooth in appearance. Hence, they are called **smooth muscles (nonstriated muscle).** * Their activities are not under the voluntary control of the nervous system and are therefore known as **involuntary muscles**. * They assist, for example, in the transportation of food through the digestive tract and gametes through the genital tract.

Answer 129

* Cardiac muscles are the muscles of heart. Many cardiac muscle cells assemble in a branching pattern to form a cardiac muscle. * Based on appearance, cardiac muscles are **striated**. They are **involuntary** in nature as the nervous system does not control their activities directly.

Answer 130

* The former has a very hard matrix due to **calcium salts** in it and the latter has slightly pliable matrix due to **chondroitin salts**.

Answer 131

* In human beings, this system is made up of **206 bones** and a few cartilages. It is grouped into two principal divisions – the axial and the appendicular skeleton. * **Axial skeleton** comprises 80 bones distributed along the main axis of the body. The skull, vertebral column, sternum and ribs constitute axial skeleton.

Answer 132

* Joints are points of contact between bones, or between bones and cartilages.

Answer 133

* Joints have been classified into three major structural forms, namely, fibrous, cartilaginous and synovial. * **Fibrous joints** **do not allow any movement**. This type of joint is shown by the **flat skull bones** which **fuse end-to-end** with the help of **dense fibrous connective tissues** in the form of **sutures**, to form the cranium. * In **cartilaginous joints**, the bones involved are **joined together with the help of cartilages**. The joint between the **adjacent vertebrae in the vertebral column** is of this pattern and it permits **limited movements**. * **Synovial joints** are characterized by the presence of a **fluid filled synovial cavity** between the articulating surfaces of the two bones. Such an arrangement allows **considerable movement**. These joints help in locomotion and many other movements. Ball and socket joint, hinge joint (knee joint), pivot joint, gliding joint and saddle joint are some examples.

Answer 134

**joint in which the rounded surface of a bone moves within a depression on another bone, allowing greater freedom of movement than any other kind of joint** 1. Here, the **joints are held together by ligaments and tendons.** 2. The ball and socket joint comprises a type of **membrane** and is present within the capsule. 3. The presence of **fluid** within the capsule enables the parts of the joints to move against each other smoothly and freely. Therefore, it is also called the **free movable joints.** most highly developed in the large [**shoulder**](https://www.britannica.com/science/shoulder) **and** [**hip**](https://www.britannica.com/science/hip) **joints** of mammals, including humans, in which it provides swing for the arms and legs in various directions

Answer 135

In this type of joint, one bone has tapped into the other in such a way that **full rotation is not possible**. This joint aid in **sideways and back-forth movement**. eg. joints between your [ulna](https://www.healthline.com/human-body-maps/ulna-bone) and [radius](https://www.healthline.com/human-body-maps/radius-bone) bones that **rotate your forearm**, and the joint between the **first and second vertebrae in your neck.**

Answer 136

Hinge joints are **like door hinges**, where **only back and forth movement** is possible. Example of hinge joints is the **ankle, elbows, and knee joints.**

Answer 137

Although the [saddle joint](https://www.healthline.com/health/saddle-joint) **does not allow rotation, it does enable movement back and forth and side to side**. For example, the **thumb** is the only bone in the human body having a saddle joint.

Answer 138

Condyloid joints are the joints with two axes which **permit up-down and side-to-side motions but no rotation**. The condyloid joints can be found at the **finger joints, carpals of the wrist, elbow and the wrist joints**. This joint is also known as a condylar, or ellipsoid joint. condyloid joint allows movement, but no rotation. Examples include your finger joints and your **jaw**.

Answer 139

also known as a plane or planar joint. This joint permit two or more round or flat bones to move freely together without any rubbing or crushing of bones. This joint is mainly found in those **regions where the two bones meet and glide on one another in any of the directions.** The **lower leg to the ankle joint and the forearm to wrist joint** are the two main examples of gliding joints.

Answer 140

F **Acetic acid (CH₃COOH)** fits into this general formula **C_x(H₂O)_y** → C₂(H₂O)₂ but is **not a carbohydrate.**

Answer 141

F * Most of them have a general formula, **C_x(H₂O)_y**, and were considered as **hydrates of carbon** from where the name carbohydrate was derived. * **Rhamnose**, C₆H₁₂O₅ is a **carbohydrate** but does not fit in this definition of **C_x(H₂O)_y**.

Answer 142

* Chemically, the carbohydrates may be defined as optically active **polyhydroxy [multiple HO groups]** aldehydes or ketones or the compounds which produce such units on hydrolysis. * Some of the carbohydrates, which are sweet in taste, are also called **sugars**. * The most common sugar, used in our homes is named as **sucrose** whereas the sugar present in milk is known as **lactose**. * Carbohydrates are also called **saccharides** (Greek: sakcharon means sugar).

Answer 143

* A carbohydrate that cannot be hydrolyzed further to give simpler unit of polyhydroxy aldehyde or ketone is called a monosaccharide. * About 20 monosaccharides are known to occur in nature. Some common examples are **Glucose**, **Fructose**, **Ribose**, **Galactose**, etc. * If a monosaccharide contains an aldehyde group [–CHO], it is known as an **aldose** and if it contains a keto group [=C=O], it is known as a **ketose**.

Answer 144

* Glucose occurs freely in nature as well as in the combined form. * It is present in **sweet fruits** and **honey**. **Ripe grapes** also contain glucose in large amounts. * Glucose is an **aldohexose [**An aldohexose is a hexose i.e. 6 C with an aldehyde group on one end**]** and is also known as **dextrose**. It is the **monomer** of many of the larger carbohydrates, namely **starch, cellulose**. * chemical structure: * hexagon made of single bonds, consisting of 5 C nd 1 O * counting anti-clockwise from O, C1 has 1 H replaced by CH2OH and rest of C has 1 H replaced by OH * however in fisher projection it has an aldehyde grp i.e. CHO-CHOH-CHOH-CHOH-CHOH-CH₂OH *

Answer 145

C₅H₁₀O₅ again contains aldehyde in fisher projection in ring form, it's a pentagon with 1 O and 4 C The ribose β-D-ribofuranose forms part of the backbone of RNA. It is related to deoxyribose, which is found in DNA.

Answer 146

* Fructose is an important **ketohexose**. It is obtained along with glucose by the hydrolysis of disaccharide, **sucrose**. * The two monosaccharides are joined together by an oxide linkage formed by the loss of a water molecule. * Such a linkage between two monosaccharide units through **oxygen atom** is called ***Glycosidic Linkage***. * str: two glucose molecules connected through an O atom; one ring's C5 and another ring's C2

Answer 147

* Galactose is a monosaccharide. When combined with glucose (monosaccharide), through a condensation reaction, the result is the disaccharide **lactose**. * The hydrolysis of lactose to glucose and galactose is catalyzed by the enzymes **lactase** and β-**galactosidase**.

Answer 148

* Carbohydrates that yield **two to ten** monosaccharide units, on hydrolysis, are called oligosaccharides. * They are further classified as **disaccharides**, **trisaccharides**, **tetrasaccharides**, etc., depending upon the number of monosaccharides, they provide on hydrolysis. * Amongst these the most common are **disaccharides**. * The two monosaccharide units obtained on hydrolysis of a disaccharide may be **same or different.** * For example, sucrose on hydrolysis gives one molecule each of glucose and fructose whereas maltose gives two molecules of glucose only. **Sucrose** == Glucose + Fructose **Maltose** == Glucose + Glucose **Lactose** == Glucose + Galactose

Answer 149

* Carbohydrates which yield a large number of monosaccharide units on hydrolysis are called polysaccharides. * Some common examples are **Starch, Cellulose, Glycogen, Gums,** * Polysaccharides are **long chains of sugars**. Polysaccharides are ***not sweet*** in taste, hence they are also called **non-sugars**. * They are threads (literally a cotton thread) containing different **monosaccharides** as building blocks. * Polysaccharides contain a large number of monosaccharide units joined together by **glycosidic linkages**. * These are the **most commonly** encountered carbohydrates in nature. * They mainly act as the food storage or structural materials. * For example, **Cellulose** is a polymeric polysaccharide consisting of only one type of monosaccharide i.e., **Glucose**. Cellulose is a homopolymer. **Starch** is a variant of this but present as a store house of energy in plant tissues. * Animals have another variant called **Glycogen**. * **Inulin** is a polymer of **fructose**. * Plant cell walls are made of cellulose. Paper made from plant pulp and cotton fibre is **cellulosic**. There are more **complex polysaccharides** in nature. * Exoskeletons of arthropods, for example, have a complex polysaccharide called chitin. These complex polysaccharides are mostly homopolymers.

Answer 150

* Starch is the main storage polysaccharide of plants. * It is the most **important dietary source** for human beings. * High content of starch is found in cereals, roots, tubers and some vegetables. * It is a polymer of α-glucose and consists of two components — **Amylose** and **Amylopectin**. * **Amylose is water soluble** polysaccharide which constitutes about 15-20% of starch. * **Amylopectin is water insoluble** polysaccharide which constitutes about 80- 85% of starch

Answer 151

* Cellulose occurs **exclusively in plants** and it is the most abundant organic substance in plant kingdom. * It is a predominant constituent of **cell wall** of plant cells. * Cellulose is a straight chain polysaccharide **composed only of β-D-glucose units**.

Answer 152

* The carbohydrates are stored in animal body as * It is also known as **animal starch** because its structure is similar to amylopectin and is rather more highly branched. * It is present in **liver, muscles** and **brain**. * Glycogen is also found in yeast and fungi. * When the body needs glucose, enzymes break the glycogen down to glucose.

NCERT-Biology Flashcards

(188 cards)