B2: Organisation

Question 1

Large multicellular organisms are made up of organ systems, explain briefly how this works.

Answer 1

Similar cells are organised into tissues, tissues are organised into organs and organs are organised into organ systems.

An organ system is a group of organs working together to perform a particular function.

Question 2

Explain what an enzyme is and how they work.

Answer 2

Enzymes are biological catalysts - they speed up useful chemical reactions. Enzymes had special shapes; each enzyme has an active site which only accepts one specific substrate molecule, for example, lipase is an enzyme specific to breaking down lipids.

Question 3

Explain why temperature affects enzyme activity.

Answer 3

The higher the temperature, the more energy they have, causing them to collide more and increasing the activity.

Question 4

What happens to enzymes when the temperature is too hot, or the pH is too high/low?

Answer 4

When conditions move past the enzyme’s optimum temperature or pH, the enzyme’s active site begins to change shape and can no longer fit the substrate molecule - when this happens, the enzyme denatures.

Question 5

Explain what molecules these types of enzymes break down:
Carbohydrases
Proteases
Lipased

Answer 5

Carbohydrases: amylase, for example, breaks down starch into maltose and other sugars.

Proteases break down proteins into amino acids.

Lipases convert lipids into glycerol and fatty acids.

Question 6

Where can these enzymes be found?

Carbohydrases

Proteases

Lipases

Answer 6

Carbohydrases, e.g. Amylase is made in the salivary glands, the pancreas and the small intestine.

Proteases are made in the stomach (it’s called pepsin there), the pancreas and the small intestine.

Lipases are made in the pancreas and the small intestine.

Question 7

Explain what bile does and state where it is made and stored.

Answer 7

Bile is made in the liver and stored in the gal bladder before it’s released into the small intestine. Bile neutralises the stomach acid, allowing the enzymes to function.

Question 8

Name the parts of the digestive system in order.

Answer 8

Salivary glands
Gullet / oesophagus
Stomach
Pancreas
Small intestine
Large intestine 
Rectum
Anus

Gall bladder
Liver

Question 9

State what tests would be done to check for:
Sugars
Starch
Proteins
Lipids

Answer 9

Sugars: Benedicts solution
Starch: Iodine solution
Proteins: Biuret solution
Lipids: Sudan III stain solution / paper

Question 10

Explain the role of the stomach in the digestive system.

Answer 10

The stomach pummels the food with its muscular walls. It also produces the protease enzyme pepsin. In order to kill bacteria and give the right pH for the protease enzymes to work it also produces hydrochloric acid.

Question 11

Explain the role of the liver in the digestive system.

Answer 11

The liver produces bile which neutralises stomach acid, making it possible for the enzymes to function.

Question 12

Explain what the pancreas does in the digestive system.

Answer 12

The pancreas produces protease, amylase and lipase enzymes, releasing them into the small intestine.

Question 13

What does the small intestine do within the digestive system?

Answer 13

The small intestine produces lipase, protease and amylase enzymes to complete digestion. It is also where food is absorbed out of the digestive system into the blood (through the villi).

Question 14

What role does the gall bladder have in the digestive system?

Answer 14

The gall bladder stored bile before it is released into the small intestine.

Question 15

What happens in the large intestine?

Answer 15

Within the large intestine, excess water is absorbed from the food.

Question 16

Explain the path that oxygen travels down to get to the lungs.

Answer 16

Trachea
Bronchi
Bronchioles
Alveoli

Question 17

How can you calculate breathing rate in breaths per minute?

Answer 17

Breaths per minute = number of breaths divided by number of minutes

Question 18

Explain the two parts of the circulatory system in the human body.

Answer 18

(The circulatory system is made up of the heart, blood vessels and blood.)

1st circuit: right ventricle puns deoxygenated blood to the lungs to take in oxygen, the blood then returns to the heart.

2nd circuit: left ventricle pumps oxygenated around the body to all other organs, the deoxygenated blood returns to the heart to be pumped out to the lungs again.

Question 19

Explain how the heart works.

Answer 19

1. Blood flows into the two atria from the vena cava and the pulmonary vein.
2. The atria contract, pushing the blood into the ventricles.
3. The ventricles contract, forcing blood into the pulmonary artery and the aorta, and out of the heart.
4. The blood then flows to the organs through the arteries, and returns through the veins.

The heart needs its own supply of oxygenated blood, which is transported through the coronary arteries which branch off the aorta and surround the heart.

Question 20

Explain the role of the pacemaker.

Answer 20

The pacemaker produces a small electric impulse which causes the muscles of the heart to contract, resetting the heart’s rhythm.

Question 21

Explain the function of arteries.

Answer 21

Carry blood away from the heart at high pressure
Strong and elastic walls
Thick walls compared to the lumen

Question 22

Describe the function of capillaries

Answer 22

Involved in the exchange of materials at the tissues
Tiny
Carry blood close to each cell
Have permeable walls to allow diffusion
Supply food and oxygen
Take away waste, e.g. Carbon dioxide
Walls only one cells thick (increases the rate of diffusion as the distance is smaller)

Arteries branch into capillaries

Question 23

Describe the function of veins.

Answer 23

Carry blood to the heart
Carry blood at a lower pressure
Bigger lumen
Valves to keep the blood flowing in one direction

Capillaries join up to form veins

Question 24

What do the red blood cells do?

Answer 24

Red blood cells carry oxygen from the lungs to all the cells in the body.
They’re shape is a biconcave disk (like a donut), giving a large surface are to absorb oxygen.
They don’t have a nucleus, allowing more room to carry oxygen.
They contain red pigment called haemoglobin.

Question 25

Explain what white blood cells do.

Answer 25

Some are able to change shape in order to get rid of unwelcome micro organisms - process called phagocytosis.
Others produce antibodies and antitoxins to fight microorganisms and neutralise any toxins produces by them.
They have a nucleus.

Question 26

Explain what platelets do.

Answer 26

Platelets are small fragments of cells that have no nucleus.
They help the blood at a wound.
Lack of platelets can cause excessive bleeding and bruising.

Question 27

Describe the role of plasma in the blood.

Answer 27

Plasma is the liquid that carries everything in the blood:

Red and white blood cells
Platelets 
Nutrients like glucose and amino acids
Carbon dioxide 
Urea
Hormones
Proteins
Antibodies and antitoxins

Question 28

Explains how stents work.

Answer 28

Stents keep arteries open that supply the blood the the muscle of the heart. Stents are tubes that are inserted into the arteries to keep them open. They lower the risk of a heart attack by slowing the build up of fatty materials. A disadvantage is that there is a risk of complications during the operation and a risk of infection from surgery.

Question 29

Explain how statins work.

Answer 29

Statins are a drug that reduce the amount of bad cholesterol in the blood, reducing the risk of a heart attack or a stroke. A disadvantage of statins is that they have side effects such as kidney failure and memory loss.

Question 30

Explain the difference between a communicable and a non-communicable disease?

Answer 30

A communicable disease is one that can be spread from person to person through things such as water and food.

A non-communicable disease cannot spread from person to person, an example would be cancer.

Question 31

Why can non-communicable diseases be costly?

Answer 31

The human cost is obvious, tens of millions of people die from non-communicable diseases per year. People who suffer with these diseases have a shorter life span and may have a lower quality of life.

Financially, the cost of treatment is huge and families often have to sacrifice much in order to afford treatment.

Question 32

How is cancer caused and what are the two types?

Answer 32

Cancer is caused by the uncontrolled growth and division, resulting in the formation of a tumour.

Benign tumours grow until there is no more room, the rumour doesn’t invade other tissues in the body. The tumour isn’t cancerous.

Malignant tumours grow and spread to neighbouring healthy tissues. They are cancerous.

Question 33

Name the parts of a plant cell in order.

Answer 33

Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Lower epidermis
Stomata
Guard cells 

Xylem
Phloem

Question 34

Explain the function of the parts of a plant cell.

Answer 34

Waxy cuticle - reduces the amount of water lost through evaporation
Upper epidermis - transparent to let light through to the palisade mesophyll
Palisade mesophyll - contains lots of chloroplasts to carry out photosynthesis
Spongy mesophyll - contain air pockets to store carbon dioxide for photosynthesis
Lower epidermis
Stomata - let air in and out
Guard cells - in charge of the stomata

Question 35

Where does translocation occur? Explain how it works.

Answer 35

Translocation occurs in the phloem. It is the transport of food substances (mainly dissolved sugars) made in the leaves to the rest of the plant. It occurs in both direction.

Question 36

Explain where transpiration occurs and what it is.

Answer 36

Transpiration occurs in the xylem. It is the transport of water and mineral ions from the roots and out of the leaves - this is called the transpiration stream.

Question 37

State the four factors that affect transpiration.

Answer 37

Light intensity
Temperature
Air flow
Humidity

Question 38

What is normal blood pressure?

Answer 38

90 - 120