Animal tissues, organs and systems 1

Question 1

What is the main function of the digestive system.

Answer 1

To digest food and absorb the nutrients obtained from digestion.

Question 2

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

Answer 2

The pancreas and the salivary gland are glands which produce digestive juices containing enzymes.

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

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

Answer 6

Absorbs water from undigested food, producing faeces.

Question 7

What is the role of enzymes in the digestive system?

Answer 7

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

Question 8

How does the shape of an enzyme affect its function?

Answer 8

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

Question 9

What is metabolism?

Answer 9

The sum of all the reactions in an organism.

Question 10

What types of metabolic reaction do enzymes catalyse?

Answer 10

• Building larger molecules from smaller molecules such as glucose to starch.
• Change one molecule to another such as glucose to fructose.
• Breaking down larger molecules into smaller molecules such as carbohydrates to glucose.

Question 11

What is the lock and key hypothesis?

Answer 11

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

Question 12

How does temperature affect enzyme action?

Answer 12

Up to a certain point, 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 optimum temperature is around 37°C.

Question 13

How does pH affect enzyme function?

Answer 13

The optimum pH for most enzymes is 7 (apart from protease 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 14

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

Answer 14

• Carbohydrases: Amylase (salivary gland and pancreas). Maltase (small intestine).
• Proteases: Pepsin (stomach). Others (pancreas and small intestine).
• Lipases: Pancreas and small intestine.

Question 15

What is the role of carbohydrases in the digestive system?

Answer 15

Carbohydrases break down carbohydrates into monosaccharides and disaccharides. Amylase break down starch into maltose, and maltase breaks down maltose into glucose.

Question 16

What is the role of proteases in the digestive system?

Answer 16

Proteases break down proteins into amino acids.

Question 17

What is the role of lipases in the digestive system?

Answer 17

Lipases break down lipids into fatty acids and glycerol.

Question 18

How are the products of digestion used?

Answer 18

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

Question 19

Where is bile made and stored in the body?

Answer 19

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

Question 20

What is the role of bile in the digestive system?

Answer 20

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

Question 20

What is the role of bile in the digestive system?

Answer 20

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

Question 21

What is the heart

Answer 21

An organ that pumps blood around the body.

Question 22

What is the purpose of the circulatory system?

Answer 22

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

Question 23

How does the double circulatory system work?

Answer 23

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

Question 24

Where does the blood pumped by the right ventricle go?

Answer 24

The lungs.

Question 25

Where does blood pumped by the left ventricle go?

Answer 25

Body tissues.

Question 26

Why is the double circulatory system important?

Answer 26

It makes the circulatory system more efficient - for example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle.

Question 27

How many chambers does the heart have and what are they called?

Answer 27

4 - 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?

Answer 29

• Aorta: 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 backflow of blood.

Question 31

What is the purpose of coronary arteries?

Answer 31

Coronary arteries supply the heart with oxygenated blood.

Question 32

Describe the process of blood flow through the heart

Answer 32

1) Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
2) The atria contract, forcing blood into the ventricles and causing the valves to shut.
3) 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 they body).

Question 33

What is the approximate value of the natural resting heart beat?

Answer 33

70 beats per minute.

Question 34

How is the heart rate controlled?

Answer 34

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 35

How can an abnormal heart rhythm be treated?

Answer 35

Irregular heart rhythms can be treated using an artificial pacemaker, which sends out electrical signals to correct the heart’s rhythm.

Question 36

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

Answer 36

• Arteries.
• Veins.
• Capillaries.

Question 37

How are arteries adapted for their function?

Answer 37

• Function: carry blood away from 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 38

How are veins adapted for their function?

Answer 38

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

Question 39

How are capillaries adapted for their function?

Answer 39

• 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 40

How do calculate the rate of blood flow?

Answer 40

Volume of blood / number of minutes

Question 41

Where are the lungs found in the body?

Answer 41

The lungs are located in the thorax (within the chest). They are protected by the ribcage and separated from the rest of the abdomen by the diaphragm.

Question 42

What tissues and organs make up the gas exchange system?

Answer 42

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

Question 43

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

Answer 43

1) Intercostal muscles contract.
2) Ribcage moves upwards and outwards.
3) Diaphragm flattens and the volume of the chest increases.
4) Increased volume results in decreased pressure.
5) Air is drawn into lungs down the pressure gradient.

The inverse occurs when air moves out of lungs.

Question 44

Describe how gas exchange occurs at the alveoli

Answer 44

• Oxygen diffuses from the alveoli into the capillary bloodstream down its concentration gradient.
• Carbon dioxide diffuses from the capillary into the alveoli down its concentration gradient.

Question 45

Describe how alveoli are adapted for gas exhange

Answer 45

• Small and arranged in clusters: larger surface area.
• Rich blood supply: maintains concentration gradient.
• Thin alveolar wall: short diffusion pathway.

Question 46

How would you calculate the breathing rate?

Answer 46

Number of breaths / number of minutes