B2 Topic 3 - Organ Systems

Question 1

Fossil records are incomplete because:

Answer 1

1) Very few dead plants and animals actually turn into fossils. Most just decay away
2) Some body parts like soft tissue tend to decay away completely
3) There are fossils yet to be discovered

Question 2

How does the pentadactyl limb provide evidence for evolution

Answer 2

1) You can see the pentadactyl limb in many species
2) In each of these species the pentadactyl limb has a similar bone structure, but usually a different function
3) The similarities in bone structure provides evidence that species with a pentadactyl limb have all evolved from a common ancestor. If they had evolved from different ancestors, it’d be highly unlike that they’d share a similar bone structure

Question 3

Growth can be measured by:

Answer 3

1) Size
2) Wet mass
3) Dry mass

Question 4

Growth involves…

Answer 4

1) CELL DIFFERENTIATION - the process by which a cell changes to become specialised for its job
2) CELL DIVISION - by mitosis
3) CELL ELONGATION - only in plants! It’s where a plant cell expands, making the cell bigger so making the plant grow

Question 5

A tissue is…

Answer 5

A group of similar cells that work together to carry out a particular function

Question 6

An organ is…

Answer 6

A group of different tissues that work together to carry out a particular function

Question 7

An organ system is…

Answer 7

A group of organs working together to perform a particular function

Question 8

The heart

Answer 8

1) The right atrium receives deoxygenated blood from the body through the vena cava
2) The deoxygenated blood moves through the right ventricle which pumps it to the lungs via the pulmonary artery
3) The left atrium receives oxygenated blood from the lungs through the pulmonary vein
4) The oxygenated blood then moves through the left ventricle, which pumps it out round the whole body via the aorta

Question 9

How is the heart adapted well to perform its function

Answer 9

1) The left ventricle has a much thicker wall than the right ventricle. It needs more muscle because it has to pump blood around the whole body, whereas the right ventricle only has to pump it to the lungs
2) Valves prevent the backflow of blood

Question 10

Job of red blood cells

Answer 10

1) RBC carry oxygen
2) They have a biconcave disc shape to have a large surface area for absorbing oxygen
3) They contain haemoglobin
4) They have NO nucleus - so they have more room for haemoglobin

Question 11

Job of White blood cells

Answer 11

1) WBCs defend against disease
2) They can ingulf bad microorganism say changing shape
3) They can produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by microorganisms

Question 12

Job of platelets

Answer 12

1) Platelets help blood clot
2) They are small fragments of cells
3) They help stop microorganisms getting in wounds

Question 13

Job of Plasma

Answer 13

1) Transports RBCs, WBCs and platelets
2) Carries nutrients like glucose and amino acids
3) Transports carbon dioxide to the lungs, where it is removed
4) Transports urea to kidneys where it is removed
5) Transports hormones from glands to target organs
6) Carries antibodies and antitoxins produced by WBCs

Question 14

Fossils found in rock layers tell us 3 things:

Answer 14

1) What the creatures and plants look like
2) How long ago they existed. Generally, the deeper the rock, the older the fossil
3) How they have evolved

Question 15

Role of arteries

Answer 15

To carry blood away from the heart

Question 16

Role of capillaries

Answer 16

These are involved in the exchange of materials with a tissue

Question 17

Role of veins

Answer 17

These carry blood to the heart

Question 18

How do arteries work

Answer 18

1) They carry blood under pressure
2) The heart pumps the blood out at high pressure so the artery walls are strong and elastic
3) The walls are thick compared to the lumen. They contain thick layers of muscle to make them strong

Question 19

How do capillaries work

Answer 19

1) They are really small
2) Arteries branch into capillaries
3) They carry blood really close to every cell in the body to exchange substances with them
4) They have permeable walls so substances can diffuse in and out
5) They supply food and oxygen, and take away wastes like carbon dioxide
6) Their walls are only one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs

Question 20

How do veins work

Answer 20

1) They take blood back to the heart
2) The capillaries eventually join up to form veins
3) The blood is at low pressure in the veins so the walls don’t need to be very thick (unlike artery walls)
4) They have a big lumen
5) They have valves to keep the blood flowing in the right direction

Question 21

Carbohydrases e.g. Amylase digest

Answer 21

Starch to sugars

Question 22

Proteases e.g. Pepsin digest

Answer 22

Protein to amino acids

Question 23

Lipase digests

Answer 23

Fat to fatty acids and glycerol

Question 24

In the mouth

Answer 24

1) Food is moistened with saliva
2) The salivary glands produce amylase enzyme in the saliva, which breaks down starch
3) Food is chewed to form a bonus before being swallowed

Question 25

In the oesophagus

Answer 25

1) Food is taken from the mouth to the stomach

2) It is lined with muscles that contract to help the bolus move along by peristalsis

Question 26

In the stomach

Answer 26

1) Food is pummelled by its muscular wall
2) The protease enzyme pepsin is produced
3) Hydrochloric acid is produced to kill bacteria and to give the right PH for pepsin to work

Question 27

In the liver

Answer 27

1) Bile is produced. Bile neutralises stomach acid and emulsifies fats

Question 28

In the gall bladder

Answer 28

1) Bile is stored before being released into the small intestine

Question 29

In the small intestine

Answer 29

1) Protease, amylase and lipase enzymes are produced to complete digestion
2) Where ‘food’ is absorbed out of the digestive system and into the body

Question 30

In the pancreas

Answer 30

1) Protease, amylase and lipase enzymes are produced and released into the small intestine

Question 31

In the large intestine

Answer 31

1) Excess water is absorbed from the food

Question 32

Benedict’s Reagent tests for

Answer 32

Sugar. It starts off blue and changes colour of sugar is present. The more sugar there is, the further the colour change goes towards brick red.

Question 33

Peristalsis involves

Answer 33

Longitudinal and circular muscles

Question 34

Waves of circular muscle contractions

Answer 34

Push the food along the gut

Question 35

Waves of longitudinal muscle contractions

Answer 35

Help keep the food in a ball

Question 36

Three features of Villi that make absorbing digested food into the bloodstream really efficient:

Answer 36

1) Big surface area - digested food is absorbed much more quickly into the blood
2) Single layer of surface cells - digested food can diffuse quickly over a short distance
3) Very good blood supply via capillary network - to assist quick absorption of digested food

Question 37

A functional food is one that has

Answer 37

Some kind of health benefit beyond basic nutrition

Question 38

What are probiotics

Answer 38

1) Live bacteria (similar to those found naturally in the gut) e.g. Bifidobacteria and Lactobacillus
2) Added to yoghurt, soya milk and supplements
3) Thought they keep your digestive system healthy and your immune system strong

Question 39

What are prebiotics

Answer 39

1) They promote growth of ‘good’ bacteria
2) Carbohydrates we cannot digest
3) Occur in leeks, onions, oats and supplements
4) May improve the health of your digestive system and may also help to strengthen your immune system

Question 40

What are plant stanol esters

Answer 40

1) Chemicals that lower blood cholesterol and reduce the risk of heart disease
2) Occur naturally in plants
3) Produced commercially by using bacteria to convert sterols into stanols
4) Sometimes added to spreads or dairy products
5) PROVEN TO WORK

Question 41

Things to watch out for about health claims

Answer 41

1) Is the report a scientific study, published in a reputable journal?
2) Was it written by a qualified person (not connected with the people selling it)?
3) Was the sample of people asked/tested large enough to give reliable results?
4) Have there been other studies which found similar results?

Question 42

3 adaptations of the heart

Answer 42

1) LHs - thick muscular wall so it can pump blood around the body
2) Valves - stop backflow of blood and maintains blood pressure
3) Septum - separates oxygenated and deoxygenated blood