B3.1 Movement of molecules in and out of cells

Question 1

How do dissolved substances move?

Answer 1

By diffusion and active transport

Question 2

How does water move across boundaries?

Answer 2

Osmosis

Question 3

What is osmosis?

Answer 3

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

Question 4

What causes water to move into or out of a cell?

Answer 4

The different concentrations of the solutions inside and outside a cell

Question 5

What do most soft drinks contain?

Answer 5

Water, sugar and ions

Question 6

What do sports drinks contain?

Answer 6

Sugars to replace the sugar used in energy release during the activity. They also contain water and ions to replace what is lost in sweat

Question 7

What happens if the water and ions are not replaced?

Answer 7

The balance of the body is disturbed and the cells do not work as efficiently

Question 8

How are some substances sometimes absorbed?

Answer 8

Against a concentration gradient

Question 9

What is the name for the method of absorption which moves against the concentration gradient?

Answer 9

Active transport

Question 10

What does active transport require?

Answer 10

Energy from repsiration

Question 11

What does active transport allow cells to do?

Answer 11

Absorb ions from very dilute solutions

Question 12

How are many organ systems specialised?

Answer 12

For exchanging materials

Question 13

How is the effectiveness of exchange area increased?

Answer 13

Having a large surface area, being thin (short diffusion path), (in animals) having an efficient blood supply and (in animals) being gaseous

Question 14

What are gas and solute exchange surfaces adapted to do?

Answer 14

Maximise effectiveness

Question 15

What does the size and complexity of an organism increase?

Answer 15

The difficulty of exchanging materials

Question 16

How is the surface area of the lungs increased in humans?

Answer 16

By the alveoli

Question 17

How is the surface area of the small intestine increased in humans?

Answer 17

By the villi

Question 18

What do the villi provide?

Answer 18

A large surface area with an extensive network of capillaries to absorb the products of digestion by diffusion and active transport

Question 19

Where are the lungs?

Answer 19

In the upper part of the body (thorax)

Question 20

What are the lungs protected by?

Answer 20

The ribcage

Question 21

What separates the lungs from the lower part of the body (abdomen)?

Answer 21

The diaphragm

Question 22

The breathing system takes air into and out of the body so that…

Answer 22

Oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air

Question 23

To make air move into the lungs the ribcage moves…

Answer 23

Out and up and the diaphragm becomes flatter

Question 24

To make air move out of the lungs the ribcage moves…

Answer 24

Inwards and down and the diaphragm contracts

Question 25

What is the movement of air in and out of the lungs called?

Answer 25

Ventilation

Question 26

In plants, carbon dioxide enters leaves by…

Answer 26

Diffusion

Question 27

In plants, most of the water and mineral ions are…

Answer 27

Absorbed by roots

Question 28

How is the surface area of roots increased?

Answer 28

By root hairs

Question 29

How is the surface area of leaves increased?

Answer 29

By the flattened shape and internal air spaces

Question 30

What do stomata do?

Answer 30

Obtain carbon dioxide from the atmosphere and remove oxygen produced in photosynthesis

Question 31

How do plants mainly lose water vapour?

Answer 31

From their leaves, most water loss takes place in the stomata

Question 32

Evaporation is more rapid in…

Answer 32

Hot, dry and windy conditions

Question 33

If plants lose water faster than it is replaced by the roots…

Answer 33

The stomata can close to prevent wilting

Question 34

What is the size of stomata controlled by?

Answer 34

Guard cells which surrounds them