Unit 1 Essentials

Question 0

What part of the phospholipid is hydrophobic?

Answer 0

The tail. It points inside the bilayer

Question 1

What is a phospholipid made up of?

Answer 1

2 fatty acid chains (lipids) and a phosphate molecule

Question 2

What part of the phospholipid is hydrophilic?

Answer 2

The head. It points outwards in the water.

Question 3

Name the type of reaction that joins monosaccharides together.

Answer 3

A condensation reaction.

Question 4

What does the rough endoplasmic reticulum do?

Answer 4

It has ribosomes that make proteins.

Question 5

How is the Golgi apparatus involved in the production of enzymes?

Answer 5

It modifies proteins and packages them into vesicles ready to be sent to the cell surface.

Question 6

Why do enzymes catalyse only one type of reaction?

Answer 6

Enzyme has a specific active site and only one type of substrate fits it.

Question 7

Describe two adaptions of the structure of alveoli for efficient gas exchange

Answer 7

Thin walls to reduce diffusion pathway. Total surface area is large.

Question 8

People who have been fire-breathers for many years often find they cannot breathe out properly. Explain why.

Answer 8

Loss of elastic tissue. Scarred tissue. Less recoil. This is fibrosis.

Question 9

How can cholera cause diarrhoea?

Answer 9

Toxin produced by the bacterium causes chloride ions to move into the lumen of the intestine. Water potential in the cells of the intestine decreases and so water moves by osmosis into the lumen.

Question 10

In areas where there are repeated outbreaks of cholera, most people who become infected by cholera bacteria do not become ill. Suggest and explain one reason why.

Answer 10

These people have produced memory cells after a previous vaccination or infection.

Question 11

Why is the process of active transport usually faster above 37 degrees?

Answer 11

Because of faster respiration and ATP production.

Question 12

Describe how you would test a food sample for starch.

Answer 12

Add iodine to the food sample. If it turns black, starch is present.

Question 13

The concentration of glucose in the blood rises after eating a meal containing carbohydrates. The rise is slower if the carbohydrate is starch rather than sucrose. Explain why.

Answer 13

Starch is digested to maltose by amylase. Maltose is digested to glucose by Maltase. Digestion of sucrose is a single step, there’s only one enzyme involved.

Question 14

Describe how a heartbeat is initiated and coordinated.

Answer 14

SAN sends a wave of electrical impulses across the atria, causing atrial contraction. Non-conducting tissue prevents the impulses from reaching the ventricles. AVN waits for the blood to fill the ventricles. Then the AVN sends impulses to the bundle of His, causing the ventricles to contract.

Question 15

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.

Answer 15

Atrium has higher pressure than ventricle so the atrioventricular valve opens. The ventricle has higher pressure than atrium so the atrioventricular valves close, ventricle has higher pressure than aorta so the semilunar valves open. Higher pressure in the aorta than ventricle so semilunar valve closes. Muscle contraction causes increase in pressure.

Question 16

How can you calculate pulmonary ventilation?

Answer 16

Pulmonary ventilation = Tidal volume x Ventilation rate

Question 17

What is the function of a mitochondrion?

Answer 17

To do aerobic respiration.

Question 18

Why can’t the organelles in a cell be seen with a light microscope?

Answer 18

Because the resolution is not great enough to distinguish between two objects of that size because light’s wavelength is too long.

Question 19

Name the constituent monosaccharides of the disaccharide sucrose.

Answer 19

Glucose and fructose.

Question 20

Name the constituent monosaccharides of the disaccharide lactose.

Answer 20

Glucose and galactose.

Question 21

Where is amylase produced and what is the product of the reaction it catalyses?

Answer 21

In the pancreas/salivary glands. Starch into maltose.

Question 22

Where is maltase produced and what is the product of the reaction it catalyses?

Answer 22

In epithelium of the small intestine. Maltose into glucose.

Question 23

How does the addition of a phosphate group to a non-functional form of an enzyme lead to the production of the functional form of that enzyme?

Answer 23

Phosphate changes the shape the enzyme’s active site. The active site is then complementary to the substrate and can form a substrate-enzyme complex.

Question 24

Why does the left ventricle require more contraction power than the right ventricle?

Answer 24

Because it needs to pump blood further all the way around the body, it produces a greater pressure.

Question 25

Suggest why the pulse felt can be used to measure heart rate.

Answer 25

The pulse is caused by pressure of blood from one contraction of the left ventricle.

Question 26

What are the processes in which substances cross the cell-surface membrane.

Answer 26

Osmosis, facilitated diffusion, active transport, phagocytosis/endocytosis, exocytosis.

Question 27

What is the process of osmosis?

Answer 27

Water molecules moving from a high water potential to a lower water potential through water channels.

Question 28

What is the process of facilitated diffusion?

Answer 28

Where molecules are transported through a carrier protein down a concentration gradient.

Question 29

What is active transport?

Answer 29

Where molecules are transported through a carrier protein against the concentration gradient using ATP from respiration.

Question 30

What is phagocytosis?

Answer 30

Engulfing by cell surface membrane to form vacuole.

Question 31

What is exocytosis?

Answer 31

Fusion of vesicle with cell surface membrane.