Dse Bio Flashcards
(204 cards)
1
Q
Transcription
A
In the nucleus ,the two DNA strands unwind, one of the strand acts as template strand, the base sequence of the DNA is transcribed to form a mRNA, by complementary base pairing. It involves the enzyme RNA polymerase.
2
Q
Translation
A
mRNA move to the cytoplasm and attaches to ribosomes (free or rough ER)
Different tRNA carries specific amino acid to the mRNA in correct sequence
The anticodon of tRNA is complementary to the codon of the mRNA
Amino acids are linked by peptide bonds to form a polypeptide
3
Q
Polypeptide
A
The polypeptide coils and folds to form protein with special confirmation
Some proteins have two or more polypeptides
4
Q
The protein may lose its active confirmation if
A
The amino acid sequence of a polypeptide change
5
Q
Inhalation
A
Intercoastal muscle contracts, the rib cage moves upward and outward
The diaphragm muscle contracts, the diaphragm becomes flatten
Volume of the thoracic cavity increases, hence the volume of the lung increase
The air pressure in the lungs decreases and becomes lower than atmospheric pressure
Air is drawn into this lungs
6
Q
Formation of tissue fluid
A
At the arteriole end of capillary bed
Pressure of blood in capillaries is higher than the pressure of fluid (hydrostatic pressure) surrounding the body cell cells
The capillary wall is thin and differently permeable
Higher blood pressure forces plasma except plasma protein out of the capillary wall to form tissue fluid
7
Q
A small amount of tissue fluid drains into the lymph capillaries by
A
Hydrostatic pressure of the tissue fluid
8
Q
Function of lymphatic system
A
Returns excess tissue fluid back to bloodstream
9
Q
Steps of using recombinant DNA technology
A
Obtain DNA fragments containing genes from human
Cut the DNA fragment of the gene and plasmid using the same restriction enzyme
Join the DNA fragment and open plasmid together using DNA ligase to form a recombinant plasmid
Introduced the recombinant plasmid into the host cell
The insulin gene is expressed in the host cell . A lot of of insulin is produced.
Isolate and purify the insulin
10
Q
Xylem function of transport
A
Xylem vessels (cell) are hollow tubes and no end walls. (No cell content)
They allow the passage of water with little resistance
11
Q
Xylem function of support
A
cell walls are thick and lignified to provide support to the plant
12
Q
Function of transport in sieve tubes
A
Sieve tubes contain cytoplasm but no nucleus this allows organic nutrients to move along with little resistance
Sieve plates have pores, allow organic nutrients to pass through with little resistance
13
Q
Companion cell has dense cytoplasm and many organelles
A
Supports metabolism of the sieve tube
14
Q
The anther
A
Produce pollen grain
15
Q
Inside pollen grain there are
A
Male gametes
16
Q
Principle of Gel electrophoresis
A
DNA fragments are negatively charged
Under an electric field , they moved toward the positive terminal of the Gel slab
Shorter DNA fragment move faster than the longer one
DNA fragments are separated into bands according to their size
After stain, a DNA fingerprint is obtained
17
Q
Principle of Gel electrophoresis
A
DNA fragments are negatively charged
Under an electric field , they moved toward the positive terminal of the Gel slab
Shorter DNA fragment move faster than the longer one
DNA fragments are separated into bands according to their size
After stain, a DNA fingerprint is obtained
18
Q
Describe the event that leads to formation of zygote after pollen grain are pollinated
A
Pollen grain land on the stigma of same species
The pollen grain develops a pollen tube
The pollen tube carries the male gamete towards the ovule in the ovary
The male gametes fuses with the female gamete
Fertilisation takes place and a zygote is formed
19
Q
Ovary of the plant
A
Becomes the fruit, the fruit protects the seeds and helps to disperse the seeds
20
Q
Ovule
A
Becomes the seed and would germinate and embryo develops into a new plant
21
Q
In terms of mechanisms of hormonal coordination, explain why the blood glucose level of a healthy person returns to normal level after a period of time?
A
When chemoreceptors in the pancreas detect an increase in the blood glucose level, it stimulates the pancreas to produce more insulin and less glucagon. insulin stimulates body cells to take up more glucose from the blood and consume more glucose for respiration. Insulin also stimulates liver cells and muscle cells to convert more glucose into glycogen for storage.
22
Q
Type 2 diabetes
A
The body cells are insensitive to insulin
23
Q
Type 2 diabetes
A
The body cells are insensitive to insulin
24
Q
Type 1 diabetes
A
Too little or no insulin because the insulin producing cells are destroyed by the immune systems
25
Lightning
Turns nitrogen in the atmosphere into nitrogen oxide which is dissolved in the rainwater to form nitrates in the soil
26
Nitrogen fixation
Convert nitrogen in soil air to ammonium compound
27
Nitrification
Ammonium compounds are turned into nitrites which are then change into nitrates by nitrifying bacteria
28
Decomposition
Decomposition breaks down organic matter and the dead bodies of the producer and consumers into ammonium compound
29
Denitrification
In poorly aerated soil denitrifying bacteria changes nitrates in the soil into nitrogen gas
30
In root nodules of leguminous plants
Nitrogen fixing bacteria convert nitrogen gas and soil air to ammonium compounds which are taken up by the leguminous plants for growth
31
The pyramid of biomass always has a broad bass
When energy is transferred from one trophic level to another, energy is lost through respiration as heat, uneaten body parts of prey , through egested faces and excretory products to the surrounding. A smaller proportion of energy is transferred to the next trophic level. Organism at the higher trophic level obtain less energy and produce less biomass. Biomass at lower trophic level is usually higher than that at the top level
32
Importance of saprophytic bacteria and fungi
They convert organic matter in dead bodies, faeces and excretory waste to inorganic nutriets. Some inorganic nutrients are absorbed by plants and enter the food web again. Decomposers are important in material recycling.
33
Characteristic of climax community
Largest variety of species, maximum biomass and greatest organism interaction
Energy input to the ecosystem is balanced by the energy consumed
If a climax community is disturbed by some external force example hill fire, it will redevelop until it attains stability again. Secondary succession takes place in this case.
34
If the required reserve ratio for banks is 100%
The maximum banking multiplier will be equal to the actual banking multiplier
The money supply will be equal to monetary base
The money supply will remain unchanged when the public deposit cash into the bank
The maximum banking multiplier will be equal to 1
35
Photochemical reaction
Occurs in the thylakoid of chloroplast
Chlorophyll absorbs light energy
The excited electron pass through the electron transport chain
The energy released is used for photophosphorylation
ADP combines with phosphate to form ATP
In photolysis, water splits to form hydrogen and oxygen.
Hydrogen is accepted by NADP to form NADPH
Oxygen gas is released as by product
36
Calvin cycle
Occurs in stroma of chloroplast
Under the action of enzymes,
Carbon dioxide combined with 5-C compound to form 2 molecules of 3-C compound
Using energy from ATP and hydrogen from NADPH, the 3-C compound is reduced to triose phosphate
Triose phosphate are used to regenerate the original 5-C compound so that Calvin cycle can repeat itself. This uses energy from ATP.
37
Oxidative phosphorylation (in the inner membrane of mitochondria)
NADH and FADH lose hydrogen
NAD and FAD regenerated
Hydrogen atom splits into hydrogen ion and electron
The electron pass through the electron transport chain
The energy released is used to form ATP
Finally, hydrogen and electron are accepted by the final electron acceptor to form water
38
Oxidation of Lactic acid
If enough oxygen, NAD and FAD are regenerated in electron transport chain
Lactic acid can be oxidised to pyruvate by NAD which is converted to acetyl-coA to enter Krebs cycle
Lactic acid can be removed
39
Inner membrane of mitochondria
The inner membrane is highly folded to form crista, providing a larger surface area to pack with enzymes and electron carriers for oxidative phosphorylation
The mitochondrial matrix contains enzymes and provide a fluid medium for Krebs cycle.
40
In the mitochondrial matrix
Contains enzyme and provides a fluid medium for Krebs cycle
41
Why does the blood lactic acid level rises after the man performs exercise?
The energy demand for skeletal muscle cell during strenuous exercise increases.
When there is insufficient supply of oxygen for completing oxidation of glucose in skeletal muscle
Skeletal muscle cells carry out anaerobic respiration to provide additional energy in very short time for muscle contraction
Lactic acid is produced in the muscle cells and diffuse to blood
Therefore the blood lactic acid level rises
42
Why athlete perform much better than non athlete
Athletes have higher ventilation rate and cardiac output then non-athletes
More oxygen is provided to the skeletal muscle cells for aerobic respiration
More energy is released for muscular contraction than non-athletes
Athletes carries out anaerobic respiration much later than non-athletes
Less lactic acid is accumulated in the muscle and muscle fatigue occurs later
43
Aerobic respiration
Glucose+oxygen ——-> co2 + water + energy
44
Anaerobic respiration
Glucose——-> lactic acid + energy
45
FSH follicle stimulating hormone
Stimulate development of follicle in the ovary
Stimulate the developing follicle to secrete oestrogen
46
Luteinising hormone secreted by pituitary gland
Triggers ovulation
Stimulates the ruptured follicles to develop into a yellow body
Stimulates the yellow body to secrete oestrogen and progesterone
47
Oestrogen secreted by developing follicles and yellow body in ovaries
Cause thickening uterine lining
Increasing but still low level of oestrogen inhibits pituitary gland from secreting FSH and LH
A high level of it stimulates the pituitary gland to secrete FSH and LH
48
Progesterone
Maintains thickness of the uterine lining
Inhibits the pituitary gland from secreting FSH and LH
49
Difference between benegin tumour and malignant tumour
Malignant tumour is surrounded by fibrous capsule, but benegin tumour is not
Malignant tumour have their own blood supply but benegin tumour do not
Cells of malignant tumours spread to other parts through the blood and lymph but cells in benegin tumours do not
50
Tumour
Caused by accumulation of mutation
51
Fluid mosaic model
Fluid nature: phospholipid lipid can move laterally
Mosaic pattern: proteins are interspersed in the bilayer in an asymmetric manner
52
The membrane is made up of
Phospholipid bilayer and protein
53
The water hating parts of the phospholipids
Point inward
54
Water loving part of the phospholipid
Point outward
55
What substances diffuse across the phospholipid bilayer
Small and fat soluble molecules (such as oxygen, carbon dioxide ,glycerol , fatty acids , vitamin A , vitamin D )by diffusion
56
What substances move across the membrane through a channel protein or carrier protein?
Water and water soluble substances by active transport (water, urea, amino acids, glucose, sodium ion, calcium ion)
57
Membrane protein on the inner membrane of mitochondria
Act as enzymes that catalyse oxidative phosphorylation
58
The three main factors lead to occurrence of infectious disease
Pathogen
Host
Environment
59
What does the pathogen do?
Resist the host, physical defence
Multiply in the whole body
Cause damage to the host cells and tissue causing disease
60
Function of antibiotics
Inhibit the formation of bacterial cell walls
Damage the cell membrane of bacteria
Inhibit synthesis of nucleic acid in bacteria which cannot carry out cell division
Inhibit protein synthesis in bacteria
61
Non-specific defence mechanism
Act against all types of pathogen
62
Humidity decrease
Transpiration decrease
Because the airspace and surrounding water vapour concentration gradient increase
63
Temperature decrease
Transpiration decrease
When temperature decrease humidity will increase
64
Very high temperature
Transpiration decrease
65
Air movement increase
Transpiration rate increase
66
At too high temperature
Stomata close
67
Light intensity increase
Transpiration rate increase
A stomata open wider at higher light intensity
68
Nitrogen function
For the synthesis of amino acids, proteins, nucleic acid and chlorophyll
69
Deficiency, symptom of nitrogen
Poor growth and yellow leaves
70
Main function of phosphorus
For the synthesis of cell membrane, ATP, and nucleic acids
Require in some enzymatic reactions
71
Phosphorus deficiency symptom
Poor growth
Leaves turned purple
Roots poorly developed
72
Potassium
Promotes photosynthesis and transport in plant
Required in some enzymatic reaction
73
Deficiency symptoms in potassium
Poor growth
Blackended leaf edges
74
Magnesium function
For the synthesis of chlorophyll
75
Deficiency, symptoms of magnesium
Poor growth
Yellow leaves known as chlorosis
76
How does the artery maintain a continuous blood flow?
Thick wall to withstand the high blood pressure due to pumping action of the heart
And when heart relaxes, artery recoil due to elasticity of wall, maintaining a continuous blood flow
77
How to regulate amount of blood flow to different organ
The arteriole wall constrict and relax
78
Vein
Large lumen to reduce resistance to blood flow
Valves present to prevent backflow of blood
Force for blood flow mainly provided by contraction of skeletal muscle
79
Allow exchange of materials between blood and body cell
Capillaries
80
Adaptive features of capillaries
Highly branched capillary bed to provide large surface area for rapid transport of materials
Total cross-sectional area is greater , blood flows slowly and allows longer time for exchange of materials
One cell thick wall to provide short distance for rapid diffusion of materials
Wall of capillaries is differentially permeable
Capillaries have no muscle
81
Adaptation of red blood cell
Have biconcave disc shape, provide large larger surface to volume ratio for the diffusion of oxygen
Flattened , provide a short distance for the diffusion of oxygen
Mature red blood cells do not have nucleus , this provides space for more haemoglobin
Packed with haemoglobin, which is an excellent oxygen carrier
82
What develops the membrane amnion?
The embryo
83
Inside aminion
Have amniotic fluid
84
Function of amniotic fluid
Act as cushion to protect embryo
Provide stable environment for development of embryo
Prevent embryo from desiccation
Allow embryo to move around easily
85
Placenta
Maternal uterine tissue and embryonic villi
86
Adaptive features of placenta for exchange of materials
1.Numerous embryonic villi which greatly increases the surface area for exchange of materials
2.The wall of the embryos capillaries and embryonic villi are very thin, provide a short distance for diffusion of material
3. There are a lot of blood capillaries which transport materials rapidly to maintain deep concentration gradient of materials between embryos blood and maternal blood
87
Different types of storage organ
Stem tuber
Bulb
Rhizome
Corm
88
Advantage of vegetative propagation
Vegetative organ stores a lot of food to support the growth of bud to new shoot
Faster way of reproduction
Does not rely on external agents for pollination . More reliable way of reproduction.
Genetic make up of offspring is identical as parents . Desirable traits can be retained in the offspring.
89
Disadvantage of vegetative propagation
Overcrowding and competition occur among offspring and parents
Transmission of disease from parents to offspring is more likely
Offspring shows no genetic variation , offspring are less adapted to change in environment
90
The anther and stigma of insect pollinated flowers are located
inside the flower
91
Sugar is used to make
Cellulose to form cell wall for new cells
92
Functions of cotyledon
Protect the delicate plumule because they cover up the plumule before emerging from the soil
Provide food for the germination of seed because they decrease in size while other structures are developing
Carry out photosynthesis to provide more food for the development of seedling because they turn green after emerging from the soil
93
Importance of water to seed germination
Can soften seed coat, the cotyledon are expanded so that the radicle can penetrate their seat coat and emerge
Water can activate the enzymes in the seed , catalyses the hydrolysis of insoluble food in the cotyledon to produce soluble food
94
Primary growth occurs in
(Increase in length)
Apical meristem of root tip and shoot tip
95
Secondary growth
(Increase in thickness)
Occurs in lateral meristem at periphery of root and stem (vascular cambium)
96
What is phototropism and the significance of such response?
It is the directional growth movement of a part of a plan in response to unilateral light
Shoots are positively phototropic, allows leaves to obtain as much as light possible for photosynthesis
Roots are negatively phototropic , allows roots to grow deeper into the soil for better anchorage
97
Auxins
Produced in the root tip and shoot tip
Auxin diffuse to the region of elongation and in shoots and roots and affect their growth
98
At low concentration of auxin
Promote root growth
99
At higher auxin concentration
Promote shoots growth but inhibit roots growth
100
At very high auxin concentration
Inhibit both root and shoot growth
101
Why the shoot bends?
Unilateral light causes a migration of auxins from light side to shaded side
More auxins diffuse to shaded side
Stimulate a greater growth on the shaded side than that of the lighter side
Resulting in greater degree of bending towards the light side
102
Cornea
Refract and focus light (80%)
103
How image on retina generate vision and brain
Photoreceptor of the retina are stimulated and produce nerve impulse. Nerve impulse are carried along the optic nerve to visual centre of the cerebrum and interpreted as vision.
104
Eustachian tube
Equalise pressure between middle ear and atmosphere
105
How is hearing produce
Pinna collects sound waves and direct them to ear drum
Ear drum converts sound waves to mechanical vibration
Ear bones amplify and transmit the vibration to the oval window
Oval window vibrates , causing the perilymph in cochlea to vibrate
Vibration in perilymph are transmitted to endolymph of cochlea
Sensory hair cell of cochlea are stimulated
Nerve impulse generated travel along the auditory nerve to auditory centre in cerebrum for interpretation and to produce sensation of hearing
106
A nerve impulse arrives at the synaptic knob at the axon terminal of a neuron
The nerve impulse stimulates the synaptic knob to release neurotransmitter
The neurotransmitter diffuse across the synaptic cleft
The neurotransmitter binds to specific protein receptors on the membrane of the next neurone
This stimulates the dendron or cell body of the next neuron to generate a nerve impulse
107
Muscle contracts to produce the pulling force
The pulling force is transmitted to the bones of the leg through inelastic tendons
Joint moves , straightens the leg and raise the leg up
108
Hinge joint
Allow movement of bones in one plane only (elbow joint)
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Ligament
Prevent dislocation during movement
Elastic and allow bones to move
110
Cartilage in the joint
Absorbs shock and reduce friction
Prevent bones from wearing away
111
Synovial membrane
Secret synovial fluid which reduce friction between bones and nourish cartilage
112
Cerebrum
Produce sensation, site of intelligence and controls voluntary actions
113
Cerebellum
Coordinate muscular movement to maintain body balance
114
Medulla oblongata
Controls involuntary reactions (example breathing rate and heartbeat)
It is a reflex centre for some reflex action (saliva secretion and swallowing)
115
Sensory area of cerebrum
Receive nerve impulse from receptor to give sensation
116
Motor area
Send nerve impulse to effectors to produce voluntary response
117
Associations area
Integrates information from different sensory areas and related information to past experience. Then the brain makes decision and send nerve impulses to motor area to give a response
118
Function of human skeleton
Support body weight
Provide surface for muscle attachment to allow movement
Protects organs (brain, spinal cord, lungs, and heart)
Red bone marrow produce blood cells
Stores minerals and lipids
119
Gene mutations
Deletion
Insertion
Substitution
Inversion
120
The effect of mutation on amino acid sequence of the polypeptide
The base sequence of mRNA is changed
The amino acid sequence of the translated polypeptide is changed
The confirmation of protein is changed
The active site of the enzyme is changed
Substrate combined with the enzyme and changed to another thing
121
Features of genetic code
Triplet codes
Degenerates , some codes code for the same amino acid
Genetic code has no gap and is read in non-overlapping manner
Genetic code is universal, same triplet code codes for same amino acid in all organism
122
Different class levels of classification
Kingdom, phylum, class, order, family, genus, species
123
To study organisms in a systematic way
To study the phylogenetic relationship of organisms
To identify organisms
124
Same species
Organisms of the same species have the greatest similarities
They can interbreed to produce fertile offspring
125
Scientific name is
Universal and enable accurate communication
126
Common name is
Misleading as different common name may be used for the same species
127
Only Animalia have no
Cell wall
128
Most eukaryotic are
Multicellular
129
Only in plantae and algae of Protista have
Chloroplast
130
Organism of different species cannot pair up during
Meiotic cell division and no gametes formed
131
Fossil record
Body fossil
Trace fossil
132
Fossil record
Body fossil
Trace fossil
133
Limitation to form fossil record
Inability to form fossils
Inability to find a complete fossil record
134
Scientists believe organic molecules were formed from
Inorganic substances
135
Scientists believe organic molecules were formed from
Inorganic substances
136
Cause of genetic variation
Mutation in the gametes or gamete producing cell
At first meiosis, Crossing overs in 2 non-sister chromatids of homologous chromosome
Random fertilisation of parental gametes
Independent assortment of homologous chromosomes
137
Isolation
Stop gene flow
138
Due to genetic variation
Different giraffes have different neck length so the long one are likely to
survive and reproduce while the shorter ones cannot
After several years, the proportion of longer necks to shorter neck increase.
139
Pesticides are
Stable, persistent chemicals
High fat solubility
Cannot be metabolised easily or excreted by organisms
140
Potential health risk to humans caused by eating selfish collective from the polluted water
Harmful algae secrete toxins in their cell and would be taken into shellfish which feed on algae and eventually pass human along the food chain
As a toxins are not metabolised and excreted out of the body
Toxins may accumulate along the food chain to a toxin level (biomagnification)
That causes poisoning in human
141
Potential health risk to humans caused by eating selfish collective from the polluted water
Harmful algae secrete toxins in their cell and would be taken into shellfish which feed on our key and eventually pass human along the food chain
As a toxins are not metabolised and excreted out of the body
Toxins may accumulate along the food chain to a toxin level (biomagnification)
That causes poisoning in human
142
Bile pigment
Breakdown of heamoglobin
143
Bile salt
Emulsify lipids into small droplets
Facilitates chemical digestion by increasing surface area of lipids for lipase to act on
144
Route of lipid soluble food into the heart
Lacteal in villi, lymphatic vessel, vein neck, anterior vena cava, right heart
145
Route of water soluble food
Blood in capillaries, hepatic portal vein, liver, hepatic vein, posterior vena cava , right heart
146
Because of ##, resulting in isolation of the two groups
Each isolated group face different sets of environments conditions
As a result, they evolved differently from each other due to natural selection
After many generation, the genetic composition were so different that
They could not breed again
147
Hormonal control of cardiac output
When person is excited or happy, the sympathetic nerve stimulates the adrenal gland to release more adrenaline into the blood. When the adrenaline reaches the heart, it stimulates the SA nodes and caridiac muscle, so the stroke volume and heart beat increase hence cardiac output increase to prepare body for emergencies
148
Hormonal control of cardiac output
When person is excited or happy, the sympathetic nerve stimulates the adrenal gland to release more adrenaline into the blood. When the adrenaline reaches the heart, it stimulates the SA nodes and caridiac muscle, so the stroke volume and heart beat increase hence cardiac output increase to prepare body for emergencies
149
Why, when Peter drank water the urine output increase
Drinking distilled water increases water potential of blood
The osmoreceptor in the hypothalamus detect the increase in water potential of blood
The pituitary gland releases less ADH into the blood circulation
The permeability of the wall of distal convoluted tubule and collecting ducts to water decreases
A smaller proportion of water is re-absorbed into the blood
A larger volume of dilute urine is formed
The urine output of Peter increases
150
Thermoregulation
Hypothalamus is responsible for thermoregulation
During the marathon run contraction of skeletal muscles generates a lot of heat
The thermoreceptor in the hypothalamus detects the rise in blood temperature
The thermoregulatory centre of the hypothalamus produces nerve impulse, cause vasodilation of the arterioles in the skin, more blood flows to the capillaries near the skin surface, more heat lost from skin surface by conduction, convection and radiation
The thermoregulatory centre of the hypothalamus produces and send nerve impulse to the sweat gland, cause the sweat gland to secrete more sweat. More heat is lost by evaporation of sweat.
151
The larger the surface area of the membrane is
The higher the rate of diffusion
152
Function of testis
Produce sperms through meiotic cell division and male sex hormones
153
Seminal vesicle, prostate gland and cowper gland
Activate and nourish sperms
Provide a medium for sperms to swim in
Neutralize the acidity of female’s vaguna
154
Three principles of contraceptive methods
1. Prevent the formation of mature follicle and ovulation
2. Prevent sperms from meeting ovum
3. Prevent implantation of embryop
155
Oral Contraceptive Pill
Contains high level of oestrogen and progesterone
Inhibiting FSH and LH from pituitary
This prevents the maturation of follicles and ovulation will not occur
156
Formation of glomerular filtrate
The high blood pressure in glomerulus squeezes blood plasma out through the walls of glomerulus and bowman’s capsule
The fluid, except the protein and blood cells, is filtered into the bowman’s capsule and forms the glomerular filtrate
157
Hypertonic group
Not enough water in the body
158
Hypotonic solution
Enough water in the body
159
Describe how the combustion of fossil fuels leads to global warming.
Burning fossil fuels produce a large amount of carbon dioxide
The carbon dioxide traps the infrared radiation (heat) reflected from earth
Leading an increase in the atmospheric temperature
160
Anaerobic bacteria decompose organic matter to form
Methane
161
Gas that cause acid rain
Sulphur dioxide and nitrogen oxides
162
Impact of acid rain on population size of plant
Acid rain enhances the release of aluminium ions from the soil which is toxic to roots
The population size of the plant decrease.
Soil minerals are dissolved and leached
Soil becomes less fertile
Population size of plant decrease
163
Different organisims are involved in
Life supporting ecological processes (e.g. water, carbon and nitrogen cycle)
164
The sewage from the farm contain pesticide, algae absorbs the pesticide
Algae eaten by shrimp and then the fish
Pesticide cannot be metabolized and excreted easily
It is accumulated through the food chain to a high level in the fish
165
Quadrat
Thrown randomly , number of different kinds of organisms enclosed is counted and recorded to increase reliability repeated sampling is carried out and a mean value is calculated
166
Limitation of quadrat
Quadrant cannot be used to sample fast moving organisms
The size of organisms must be small enough so that a reasonable number of individuals is enclosed by the quadrat
Quadrats can be used only when the habitat is fairly uniform
167
Line transact
Only shows the presence or absence of species it cannot show the abundance of different species as no area is measured
168
The scientist study defect of humidity on the distribution of Woody plants in the field briefly describe the sampling procedures
Place a transact from far from the stream to near the stream
Place a quadrat along the transact at regular intervals
Count number of woody plants in the quadrat and record the results
169
Rice is at lower trophic level. Shorter food chains have a fewer
Energy loss
170
Bottom trawling leads to destruction in aquatic habitats like seagrass and coral reefs so this reduce
Food supply to other fishes and lead to death of underwater organisms
171
Cyanide fishing will kill corals
Loss of breeding ground so the population of many species decreases
172
Why the shoot should be cut underwater
To prevent blocking of the xylem vessels by air bubbles
173
174
On a hot sunny afternoon, the plant becomes wilted and it’s stem bends
The stem of the plant is mainly supported by the turgidity of the thin walled cells in pith
Under a hot sunny condition, the rate of water loss by transpiration is greater than the rate of water absorption
The cells in the region have net loss of water and become flaccid
They cannot support the plant
175
The whole leaf structural adaptation
Leaves are broad and flat
They are also large in number in a plant. These provides a large surface area for diffusion of gases.
Leaves are thin
This shortens the distance of diffusion of gases between the plant body and the atmosphere
176
Internal structure of the leaves structural adaptation
Spongy mesophyll cells are loosely packed. This provides a large surface area for diffusion of gases.
Numerous airspace among the spongy mesophyll cells this allows gases to diffuse freely
Water on the surface of mesophyll cells, this allow gases to dissolve and then diffuse into or out of the cell
177
Tissue
Phloem and xylem
178
Cells
Sieve tube and xylem vessel
179
Pith in the stem
Store organic nutrients and to support the plan by turgidity of thin wall cell
180
Leaves are supported by the thin wall cell of
Mesophyll cells, cortex and pith
181
Xylem vessels and tissue of young dicot plant contain thick wall cell which
Contain lignin which makes the cells hard and rigid
182
When we inhale
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles (in lungs)
Air sacs (in lungs)
183
Bronchioles have no
Cartilage
184
Trachea cartilage is
C-shaped
185
Adaptive features of air sacs for gas exchange
There are large number of air sacs
Provide a very large surface area for the diffusion of gases
Walls of air sacs are very thin
Air sacs are one celled thick
Reduce diffusion distance of gases
Inner surface of air sacs are moist
Dissolve in water film before diffusion takes place
Rich supply of cappilaries
Allows rapid transport of gases to and from the air sacs
Walls of Air sacs are in close contact with capillaries
Reduce diffusion distance of gases
186
Mucus secreting cells
Secrete mucus and traps, dust particles and microorganisms in the inhaled air
Moistens the inhaled air
187
Cilia of ciliated epithelial cells in the lining
Sweep the mucus toward the pharynx
188
Rich supply of blood vessels in the nasal cavity
Warms the inhaled air
189
Paul broke his ribs in an accident. Why did the left lung collapse?
The left plural membrane is pierced by the ribs
Air enters the plural cavity
Plural cavity has a higher air pressure
The lung is elastic and collapse
190
When transfer payments, salary tax allowance and salary tax rate increase
Disposable income increase
Consumption increase
Aggregate demand increase
191
When profit tax rate and general sales tax increased
The investment and aggregate demand decrease
192
Hydrochloric acid in stomach
To provide an acidic medium for the action of pepsin
To kill most bacteria in food (body defence)
193
Flowchart of water soluble
Blood capillaries in villi
Hepatic portal vein
Liver
Hepatic vein
Posterior vena cava
Right heart
194
Flow chart of lipid soluble food
Lacteal in villi
Lympathic vessel
Vein in neck
Anterior vena cava
Right heart
195
Formation of tissue fluid
At arteriole end, the pressure of blood is higher than that of tissue fluid.
The capillary wall is thin and differentially permeable.
The higher blood pressure forces plasma except plasma protein out of capillary wall
196
Features of veins
Large lumen of the veins reduce the resistance to the blood flow inside the veins
Valves are present in veins to prevent the backflow of blood
The force of bloodflow is mainly provided by the contraction of the skeletal muscles lying next to the vein
197
Observable features of villus that adapts for absorption
It has a thin epithelium (one cell thick)
Provides a short distance for diffusion of food molecules into the blood
It has lacteal and capillary network to carry abosorbed food away quickly
It keeps a steep concentration gradient of food molecules to facilitate absorption
198
After gallbladder was removed state and explain effect on digestion of fatty food
There is less bile salt to emulsify lipids into oil droplets
The surface area for pancreatic lipase is to act on is less
Less fat in fatty food digested
199
In arteries and arterioles
Close to the heart so the blood pressure is high
Due to pumping action of heart
200
In capillary
Resistance in the vessel increase due to lumen size decrease lead to significant drop in blood pressure along the capillaries
201
In venule and vein
Blood has overcome high resistance of the blood vessel walls after travlleing a very long distance away from the heart
Blood pressure becomes very low
202
How does oxygen in the air sac reach the blood in the normal situation
Oxygen dissolves in the water film on the inner surface of air sac and diffuse across the wall of the air sack and blood capillary wall and into the blood
203
How is Water transported from the root to xylem
Transformation pull continues to draw water from the xylem
Lowering the water potential of neighbouring cells
Absorption of water at root maintains a high water potential there
Water moves from root to xylem along the water potential gradient across the root
204
