Module 2: Organisation of Living Things

Question 1

What are unicellular organisms?

+ example

Answer 1

• Contain only one cell responsible for all life processes
• Simple structure
• Limits metabolic reactions
• Large surface area for all substances to diffuse across
• All prokaryotes are unicellular
• EXAMPLE: Bacteria (salmonella)

Question 2

What are multicellular organisms?

+ example

Answer 2

• Made up of different types of cells
• Similar cells grouped together that communicate to perform specialised functions that combine together for efficient functioning
• Rely less on diffusion and are less efficient
• All cells have the same DNA
• Could not survive by themselves
• EXAMPLE: Animals and Plants

Question 3

What are colonial organisms?

+ example

Answer 3

• Cells that form a cooperative group (colony) but can survive on their own
• Could be classed as a single celled organism
• More efficient as a colony
• EXAMPLE: Blue-bottle

Question 4

Example of differentiated cells in humans:

Answer 4

Function:To carry oxygen to cells and remove carbon dioxide – RBCs travel through tiny capillaries to reach every single cell in our bodies
Nucleus-No – to limit size
Organelles-No – to limit size
Size- Red – 7-8um

Question 5

What is the structure of organised life:

Answer 5

cell
tissue
organ
organ system
organism

Question 6

cell function

Answer 6

smallest unit that can carry out lifes activities

Question 7

tissue function

Answer 7

group of cells working together to perform specific job

Question 8

organ

Answer 8

group of tissues working together to perform specific job

Question 9

organ system function

Answer 9

group of organs working together to perform specific job

Question 10

Example of organised life;

Answer 10

cell- Cardiomyocytes - These cells must be able to shorten and lengthen their fibres and the fibres must be flexible enough to stretch in order to create a ‘pumping’ motion in the heart.
tissue- Cardiac muscle tissue - Endocardium, Myocardium and Epicardium. This is a specialised form of muscle tissue
organ- heart
organ system- cardiovascular system
organism- humans

Question 11

organelle summary:

Answer 11

Organelles are the subunit of a cell and consist of a group of functioning biomolecules. Organelles take part in the chemical reactions and interactions in the cellular processes of an organism. A few examples include nucleus and chloroplasts (plant cells), and Golgi bodies and mitochondria (animal cells).

Question 12

tissue summary

Answer 12

tissue is combination of different types of cells which perform specialized functions. The group of cells that form a tissue are not necessarily identical, but they usually have the same origin i.e. cardiac muscle tissue consists of different types of muscle cells.

Question 13

nervous tissue

Answer 13

Nervous tissues form organs like the brain and the spinal cord and are capable of sending and receiving electrochemical messages

Question 14

muscle tissue

Answer 14

Muscle tissues are actively contractile, meaning they can contract and expand. These tissues are useful for producing force and motion.

Question 15

connective tissue

Answer 15

Connective tissues are fibrous in nature, and they are made up of cells that are separated by an extracellular matrix.

Question 16

epithelial tissue

Answer 16

• Epithelial tissues cover the surface of body organs.

Question 17

what are the four types of tissue in the human body?

Answer 17

There are four types of tissue in the human body: nervous, muscle, connective, and epithelial tissues.

Question 18

organ summary

Answer 18

An organ performs certain functions with the help of different tissues. The major organs of animals include the lungs, brain, liver and heart whereas roots, stem, and leaves are the different organs of plants.

Question 19

how are organs classified?

Answer 19

on the basis of the functions they perform. For example, in case of animals, the tongue, ears, eyes, skin, and nose are sensory organs, and ovaries and testes are reproductive organs. These units are formed by tissues that serve a common function.

Question 20

organ system summary

Answer 20

Organs working together to perform certain functions form organ systems. Examples are the circulatory system in animals, and the vascular system in plants. The organs in an organ system are interdependent, i.e. they work in harmony to carry out various body functions

Question 21

organism summary

Answer 21

An organism could either be unicellular or multicellular. The ones that are closely related can be grouped together under a single genus. An organism can be defined as the fully functional form of a living being that can thrive in a particular environment.

Question 22

What is a specialised cell?

Answer 22

Specialised cells make up tissues with different types of tissues forming organs that carry out particular function within an organ.

Question 23

what are stem cells?

Answer 23

All specialised cells originate from cells that are known as stem cells. These stem cells are undifferentiated and are able to divide many times of a long period and become specialised.

Question 24

What happens to cells once they have specialised?

Answer 24

Once cells have become specialised to form a particular type of cell, they lose their capacity to develop into other types of cells.

Question 25

What is the relationship between cell structure and function?

Answer 25

The cells of those parts of the body include in exchanging substances with the environment have special structural features to increase their surface area to volume ratio allowing them to exchange the required materials more efficiently. EXAMPLE – Alveoli Cells may be flattened to increase their surface area to volume ratio that allow for the more efficient exchange of substances.

Question 26

Skeletal muscle

Answer 26

Skeletal muscle – long and have striation which are caused by the arrangement of the actin and myosin in them. They are attached to the bones and they cause movement. They are voluntary muscles because they require conscious thought to function

Question 27

cardiac muscle

Answer 27

fibres are present in the heart and also have striations, the individual cells have connection junctions that are necessary or the coordinated beating of the heart

Question 28

smooth muscle

Answer 28

do not have striation and their contractions push substances through specialised organs such as the gastrointestinal tract, the blood vessels and the urethra which leads from the bladder.

Question 29

What is the difference between voluntary and involuntry?

Answer 29

Muscles that are under your conscious control are called voluntary muscles. Muscles that are not under your conscious control are called involuntary muscles

Question 30

Meristematic tissue:

Answer 30

(Plant cell) • Found at the tips of roots and shoots • In woody plants it can also be found in buds and in a ring around the stem • Inside these tissues’ cells divide to produce new growth • Cube shaped and very small

Question 31

CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:

Answer 31

surface area thin moist surface close proximity to transport system greater concentration of gas on one side

Question 32

CHARACTERISTICS OF GAS EXCHANGE SYSTEMS: | surface area

Answer 32

* Enhanced by folding, branching or flattening | * Allows for a higher rate of diffusion and remove carbon dioxide quicker

Question 33

CHARACTERISTICS OF GAS EXCHANGE SYSTEMS: | thin moist surface

Answer 33

* Easier diffusion | * Decreases distance for gas to travel

Question 34

CHARACTERISTICS OF GAS EXCHANGE SYSTEMS: | close proximity to transport system

Answer 34

• Efficient transport

Question 35

CHARACTERISTICS OF GAS EXCHANGE SYSTEMS: | greater concentration of gas on one side

Answer 35

• To ensure the concentration gradient is upheld

Question 36

ROLE OF THE RESPIRATORY SYSTEM

Answer 36

* Work with the cardiovascular system * Transports oxygen to every cell and remove carbon dioxide. * Needs air which must be taken in from the environment * Oxygen in atmosphere transferred into the blood * Different animals use the respiratory system differently

Question 37

Respiratory system in insects:

Answer 37

Insects have a system of tubes, called tracheae, instead of lungs. These tracheae penetrate right through the insect's body. Air enters the tracheae by pores called spiracles. These spiracles are found on each side of the insect's abdomen. Each segment of the abdomen has a pair of spiracles. The air passes into the tracheae which branch into smaller and smaller tubes, in a similar way to the bronchioles in our lungs. The tracheae finally come to an end in the tissues which are respiring. Here in the tissues the oxygen is taken from the air in the tracheae. At the same time carbon dioxide enters the tracheae so that it can be expelled from the body.

Question 38

Respiratory system in reptiles:

Answer 38

All reptiles breathe through their lungs. The reptile lung has a much greater surface area for the exchange of gases than the lungs of amphibians. Many reptiles' lungs have little sacs called alveoli, across which gas is exchanged

Question 39

respiratory system in fish:

Answer 39

Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx.

Question 40

Pharynx:

Answer 40

Connects the nasal cavity & mouth to the larynx. It is a pathway for both food and air.

Question 41

Larynx:

Answer 41

Responsible for ensuring food & air go into the proper channels.

Question 42

Trachea:

Answer 42

Called windpipe. Is very flexible & mobile. It contains cells which remove foreign particles from the air. Divides into two bronchi

Question 43

Epiglottis

Answer 43

A flap of cartilage which prevents food entering.

Question 44

bronchi:

Answer 44

There are two bronchi leading to each lung. | The bronchi further divide into bronchioles.

Question 45

Bronchioles:

Answer 45

To ensure that incoming air is supplied to each alveolus.

Question 46

lungs

Answer 46

Enclose the structures of the body responsible for gas exchange Bronchioles & alveoli. The lungs are mainly air spaces where internal gas exchange occurs.

Question 47

alveoli:

Answer 47

Alveoli are small air-filled sacs. - Increased SA - Thin moist membrane - Near blood supply (capillaries)

Question 48

capillaries

Answer 48

Gas exchange occurs through diffusion (concentration gradient).

Question 49

stomata and gas exchange in plants:

Answer 49

Most gaseous exchange in plants takes place through the stomata and lenticels. When the stomata are open, gases are able to diffuse through them, but no gas exchange occurs when stomata are closed.

Question 50

At what time does respiration occur in plants?

Answer 50

night

Question 51

at what time does photosynthesis occur in plants?

Answer 51

day

Question 52

What is the stomata?

Answer 52

``` • Tiny pores that cover epidermis • Gas enters and leaves • Each has a pair of guard cells - Open and close throughout day - Have chloroplast - Reduce water loss • Stomata in grooves - as leaf dehydrates grooves close - reduced water loss • Stomata at bottom of pits - reduced water loss • Sunken of stomata - reduced water loss ```

Question 53

Why do multicellular organisms need transport systems?

Answer 53

Cells near the centre of multicellular organisms could not rely on diffusion of substances from the outside alone and therefore require a transport system to deliver nutrients, gases and remove wastes.

Question 54

Circulatory system characteristics (multicellula rorganisms)

Answer 54

* An efficient carrying capacity * A large surface area for the exchange of materials * The effective movement of fluid * The ability to regulate movement of fluid according to needs

Question 55

heterotrophs

Answer 55

Organisms that feed on others because they cannot provide their own energy supply

Question 56

autotrophs

Answer 56

organisms that can make their own energy and do not depend on others.

Question 57

NUTRITIONAL REQUIREMENTS OF HETEROTROPHS

Answer 57

Obtaining nutrients and energy from food involves several steps: 1. Ingestion – intake of food (eating) 2. Digestion – breakdown of food into soluble molecules that can be easily absorbed 3. Absorption – basic units of food absorbed into the bloodstream 4. Assimilation – turning the ‘food’ into tissue 5. Egestion – elimination of wastes

Question 58

Mechanical digestion:

Answer 58

Mechanical breakdown (Physical) – chewing, churning, moving

Question 59

Teeth and mechanical digestion

Answer 59

1. Incisors (front teeth): used to grasp, hold and bite food 2. Canines (‘eye’ teeth or ‘fangs’): used for stabbing and gripping prey and for tearing flesh 3. Premolars (cheek teeth): used for chewing and for cutting flesh and cracking hard body parts (e.g. bones) 4. Molars (back teeth): used for grinding and chewing

Question 60

chemical digestion:

Answer 60

(Enzymes) - Break down large complex molecules into simpler molecules

Question 61

structure of the small intestine:

Answer 61

long with a large surface area (good for absorption). It has an internal surface compromised of millions of tiny folds called villi.

Question 62

function of the small intestine:

Answer 62

absorbs nutrients and minerals from food like glucose, water and salts. Enzymes produced in the pancreas, small intestine, and bile from the liver and gall bladder break down food products to facilitate nutrient and water absorption. It has many blood vessels that absorb nutrients and waste products and then delivers them to circulatory system.

Question 63

xylem structure:

Answer 63

Xylem vessels are long, narrow, hollow tubes containing no living material and impregnated with bands or spirals of lignin. They are joined end to end and provide a continuous pathway from the roots through the stem and to the leaves for water transport.

Question 64

lignin fucntion:

Answer 64

provides strength to stop the vessels from collapsing.

Question 65

tracheids fucntion:

Answer 65

transport water and are elongated with end walls that taper to a point and also impregnated with lignin

Question 66

fibres structure and function:

Answer 66

Fibres are also elongated and lignified, providing support to the xylem tissue.

Question 67

Movement of water in transpiration:

Answer 67

* Explained by Transpiration cohesion theory * Water against gravity * Transpiration from stomata (loss of water) created negative pressure * Negative pressure pulls the water upwards

Question 68

How is the movement of water assisted?

Answer 68

Assisted by stickiness - Water molecules attracted to each other, temporary bonds that ‘stick’ together, Cohesive and adhesive forces (attractive forces between water molecules)

Question 69

Cohesion/ adhesion:

Answer 69

The ability of water molecules to stick to other water molecules due to high intermolecular forces

Question 70

transpiration:

Answer 70

Loss of water from plants by evaporation of water vapour through the stoma of plant leaves.

Question 71

negative pressure:

Answer 71

When an area of lower pressure than the other surrounding it. Creates a ‘pulling’ force

Question 72

Phloem function:

Answer 72

sugar transport tissue in plants

Question 73

Sieve tub elements

Answer 73

living cells without cytoplasm and mitochondria but without other organelles

Question 74

sieve plates

Answer 74

the perforated transverse walls of the sieve elements which allow sap to flow from one element to the next

Question 75

companion cells

Answer 75

associated with each sieve element and they are responsible for keeping them alive

Question 76

translocation

Answer 76

is the movement of materials in plants from the leaves to other parts of the plant. Nutrients, mainly sugars, are created in the leaves during photosynthesis. These are then transported throughout the plant through phloem.

Question 77

Translocation source:

Answer 77

Place that produces or stores sugar (leaves and roots)

Question 78

translocation sink:

Answer 78

Place in need of sugar

Question 79

translocation process:

Answer 79

* Transports sugars from sources to sinks * Uses active transport to go against the concentration gradient * Actively transported from a source, creates an area of high concentration, which causes the water to passively more from the xylem to dilute sugar * Creates temporary pressure causing the movement of materials towards the various sinks

Question 80

What are the differences between xylem and phloem?

Answer 80

``` Xylem = dead cells, direction = up, movement of water and minerals Phloem = living cells, direction = up and down, movement of sugars ```

Question 81

red blood cells

Answer 81

45% Disc shaped cells that contain haemoglobin Transport oxygen, carbon dioxide and haemoglobin

Question 82

white blood cells

Answer 82

<1% Bigger than red blood cells Transports antibody into the plasma to fight pathogens

Question 83

platelets

Answer 83

<1% Small, colourless, irregular, sticky surfaces Clumps blood to control bleeding

Question 84

plasma

Answer 84

54% Liquid mainly made up of water Carries nutrients (glucose, amino acids, proteins, ion, waste products and small amounts of carbon dioxide

Question 85

veins

Answer 85

Veins return blood to the heart and have thinner walls than those of the arteries. The walls are thinner, and the veins are compressed, propelling the blood towards the heart. Veins have valves which prevent blood from flowing backwards as they work like one-way swing doors.

Question 86

arteries

Answer 86

Arteries carry blood away from the heart with a strong structure that is able to withstand the high pressure in which the blood is moving. The tissue is made from elastic and collagenous fibres that allow varying volumes of blood to move through at high pressure

Question 87

capilalries

Answer 87

Capillaries bring blood into close contact with tissues, enabling the exchange of chemical substances between cells and the bloodstream. Their walls are only one cell thick allowing diffusion which iis a slow process, therefore their internal diameter is only slightly larger than red blood cells, slowing down the flow of blood.

Question 88

open circulation

Answer 88

* Fluid is not combined to vessels * Circulation is slow * Transports nutrients not oxygen * Found in arthropods e.g. insects and mollusc

Question 89

closed circulation

Answer 89

* Blood moves through the body enclosed in a network of tubes of different sizes that lead to and away from the heart * Blood circulation is rapid * Nutrients, wastes and gases are carried by blood * Found in larger, active animals e.g. mammals, amphibians, birds and fish