B2 - Organisation

Question 1

What is a cell?

Answer 1

The basic building block of a living organism.

Question 2

What is a tissue?

Answer 2

A group of cells with a similar structure and function working together.

Question 3

What is an organ?

Answer 3

A collection of tissues working together to perform a specific function.

Question 4

What is an organ system?

Answer 4

A group of organs working together to perform specific functions.

Question 5

What is the main function of the digestive system?

Answer 5

To digest food and absorb the nutrients obtained from digestion.

Question 6

What is the role of the pancreas and the salivary gland in the digestive system?

Answer 6

They are glands which produce digestive juices containing enzymes.

Question 7

What is the role of the stomach in the digestive system?

Answer 7

Produces hydrochloric acid which kills any bacteria present and provides the optimum acidic pH for the enzyme to function.

Question 8

What is the role of the small intestine in the digestive system?

Answer 8

The site where soluble food molecules are absorbed into the bloodstream.

Question 9

What is the role of the liver in the digestive system?

Answer 9

Produces bile (stored in the gall bladder) which emulsifies lipids and allows the lipase enzyme to work more efficiently.

Question 10

What is the role of the large intestine in the digestive system?

Answer 10

Absorbs water from undigested food, producing faeces.

Question 11

What is the role of enzymes in the digestive system?

Answer 11

Enzymes act as biological catalysts which speed up the breakdown of food without being used up.

Question 12

How does the shape of an enzyme affect its function?

Answer 12

Enzymes have a specific active site which is complementary to their substrate.

Question 13

What is metabolism?

Answer 13

The sum of all the reactions in a cell or an organism.

Question 14

What types of metabolic reactions do enzymes catalyse?

Answer 14

• Building larger molecules from smaller molecules e.g glucose to starch.
• Changing one molecule to another e.g glucose to fructose.
• Breaking down larger molecules e.g carbohydrates to glucose.

Question 15

Explain the lock and key theory for how enzymes work?

Answer 15

The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex.

Question 16

How does temperature affect enzyme action?

Answer 16

• Increasing temperature increases enzyme action, as molecules have a higher kinetic energy.
• Above a certain temperature, the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the reaction. The ideal temperature is around 37°.

Question 17

How does pH affect enzyme function?

Answer 17

• The ideal pH for most enzymes is 7 (apart from proteases in the stomach).
• If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.

Question 18

What do carbohydrases, proteases and lipases do?

Answer 18

• Carbohydrases convert carbohydrates into simple sugars.
• Proteases convert proteins into amino acids
• Lipases convert lipids into fatty acids and glycerol

Question 19

Where are carbohydrases, proteases and lipases produced in the body?

Answer 19

• Carbohydrases: - amylase - salivary gland and
  pancreas.
  - maltase - small intestine.
• Proteases: - pepsin - stomach.
  - others - pancreas and small intestine.
• Lipases: pancreas and small intestine

Question 20

How are the products of digestion used?

Answer 20

• They are used to build bigger molecules such as carbohydrates and proteins.
• Glucose is used as a substrate in respiration.

Question 21

Where is bile made and stored in the body?

Answer 21

Bile is made in the liver and stored in the gallbladder.

Question 22

What is the role of bile in the digestive system?

Answer 22

• Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach.
• Bile emulsifies lipids to form droplets - this increases the surface area for the lipase enzyme to work on.

Question 23

What is the purpose of the circulatory system?

Answer 23

Carries oxygen and other useful substances to bodily tissues, and removes waste substances.

Question 24

How does the double circulatory system work?

Answer 24

• One pathway carries blood from the heart to the lungs - where the gaseous exchange of oxygen and carbon dioxide takes place.
• One pathway carries blood from the heart to the rest of the organs.

Question 25

What does ‘LORD’ stand for?

Answer 25

L - Left
O - Oxygenated
R - Right
D - Deoxygenated

Question 26

Why is the double circulatory system important?

Answer 26

It makes the circulatory system more efficient.

Question 27

What are the four chambers of the heart called?

Answer 27

• Right atrium
• Right ventricle
• Left atrium
• Left ventricle

Question 28

Why is the wall of the left ventricle thicker?

Answer 28

The left ventricle has to pump blood at a higher pressure around the whole body.

Question 29

What are the four main blood vessels associated with the heart and what are their roles?

Answer 29

• Aorta (left) - carries oxygenated blood from the heart to the body.
• Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart.
• Vena cava (right) - carries deoxygenated blood from the body to the heart.
• Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.

Question 30

What is the purpose of valves in the heart?

Answer 30

Prevent the backflow of blood.

Question 31

What is the purpose of coronary arteries?

Answer 31

They supply the heart muscle with oxygenated blood.

Question 32

Describe the process of blood flow through the heart.

Answer 32

• Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
• The atria contract, forcing blood into the ventricles and causing valves to shut.
• After the ventricles contract, blood in the right ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body).

Question 33

How is the heart rate controlled?

Answer 33

Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle to contract.

Question 34

How can irregular heart beats be treated?

Answer 34

Using an artificial pacemaker, which sends out electrical signal to correct the heart’s rhythm.

Question 35

What are the three types of blood vessel in the body?

Answer 35

• Veins
• Arteries
• Capillaries

Question 36

How are arteries adapted for their function?

Answer 36

• Function: carry blood away from the heart.
• Thick muscle layer - adds strength to resist high pressure.
• Thick elastic layer - allows arteries to stretch and recoil - in order to withstand high pressure.

Question 37

How are veins adapted for their function?

Answer 37

• Function: carry blood towards the heart.
• Wide lumen - enables low pressure.
• Valves - prevent backflow of blood.

Question 38

How are arteries capillaries for their function?

Answer 38

• Function: enable transfer of substances between the blood and tissues.
• Walls are one cell thick - short diffusion path.
• Permeable walls - substances can diffuse across.
• Narrow lumen - blood moves slowly - more time for diffusion.

Question 39

How would you calculate the rate of blood flow?

Answer 39

Volume of blood / number of minutes

Question 40

What tissues make up the gas exchange system?

Answer 40

• Trachea
• Intercostal muscles
• Bronchi
• Bronchioles
• Alveoli
• Diaphragm

Question 41

Explain how the lungs are ventilated by the action of intercostal muscles?