B3.1

Question 1

What is osmosis?

Answer 1

The diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules

Question 2

Why is putting salt on a snail cruel?

Answer 2

Because the salt causes the water to move out from the slug by osmosis and this dehydrates the slug

Question 3

How is the effectiveness of an exchange surface increased?

Answer 3

~ A large surface area
~ Being thin, to provide a short diffusion path
~ Being moist
~ Having an efficient blood supply (in animals)
~ Being ventilated

Question 4

Why does glucose not diffuse through partially permeable membranes?

Answer 4

They’re too big

Question 5

What happens if blood cells are in dilute solutions?

Answer 5

The water would move in and the membrane of the cells would not be able to cope with the high pressure and would burst

Question 6

What happens if blood cells are in concentrated solutions?

Answer 6

The water in them would move out and this would cause the blood cell to shrink

Question 7

Why is it important that the concentration of the plasma in the blood is kept at the right level?

Answer 7

As it will affect our red blood cells, and cause them to burst in dilute solutions or shrink in concentrated solutions

Question 8

Why don’t cells in plant cells burst if there is a dilute or concentrated solution of water?

Answer 8

Because of their strong cell wall

Question 9

What does exercise cause in the body?

Answer 9

~ Blood glucose to decrease

~ The body to sweat out water and ions such as sodium and potassium (electrolytes)

Question 10

What do sports drinks claim to do?

Answer 10

Replace water, mineral ions and sugar lost through sweating

Question 11

What are advantages of sport drinks?

Answer 11

~ Water doesn’t contain enough sodium and carbohydrates needed by the body
~ Water doesn’t have a desirable taste so less will be consumed

Question 12

What are disadvantages of sport drinks?

Answer 12

They’re good for endurance athletes but not for people who work out every now and then

Question 13

What is active transport?

Answer 13

When substances move against the concentration gradient (from an area of low concentration to an area of high concentration)

Question 14

What does the process of active transport require?

Answer 14

Energy from respiration

Question 15

How is active transport used in the body?

Answer 15

~ It moves glucose from the small intestine back into the blood
~ It moves glucose from the kidney tubules back into the blood

Question 16

What is gaseous exchange?

Answer 16

The exchange of carbon dioxide and oxygen between the blood and the air in the lungs

Question 17

What is the diaphragm?

Answer 17

A muscle that separates the thorax and abdomen

Question 18

What is transpiration?

Answer 18

The process of water evaporating from the leaves

Question 19

What environmental conditions will increase the rate of transpiration?

Answer 19

• Hot weather
• Dry weather (low humidity)
• Windy conditions

Question 20

What do guard cells do?

Answer 20

Open and close the stomata depending on the levels of water in the plant

Question 21

How can you test the rate of transpiration?

Answer 21

• Cobalt chloride paper turns from blue to pink in the presence of water
• Seal a plastic bag over a leaf on a plant
• Measure how quickly the cobalt paper turns pink

Question 22

Why does a plant have root hair cells?

Answer 22

To increase its surface area in the roots which increases the absorption of water and mineral ions