Cell Membrane

Question 1

What are the leaves’ role in a plant?

Answer 1

• The leaves contain most of a plant’s photosynthetic cells
• Photosynthesis requires efficient gas exchange between air surrounding the leaf and the photosynthetic cells, whilst minimising water loss

Question 2

What is the role of the lungs in mammals?

Answer 2

Gas exchange between air in the alveoli and the blood, to supply cells with oxygen for aerobic respiration and to remove carbon dioxde

Question 3

What features do exchange surfaces typically have?

Answer 3

• Large surface area to increase rate of diffusion
• Thin wall to provide a short diffusion path
• Dense network of blood vessels to maintain a concentration gradient

Question 4

How do substances move by active transport?

Answer 4

From a low concentration area to a high concentration area against the concentration gradient

Question 5

How is the small intestine adapted to it’s role?

Answer 5

• High folded surface lined with specialised intestinal epithelial cells increases surface area
• Only one layer of epithelial cells covers the surface of each villus decreases the diffusion distance
• Each villus has a good blood supply which maintains a concentration gradient

Question 6

How are the lungs adapted to their role?

Answer 6

• Millions of alveoli collective provide a huge surface area
• The wall of each alveolus is one cell thick, with a moist lining and excellent blood supply which decreases diffusion distance and maintains a concentration gradient

Question 7

What is a solution?

Answer 7

A solvent and a solute mixed together

Question 8

How does temperature affect diffusion?

Answer 8

The higher the temperature, the more kinetic energy the particles have. They move faster so there is a higher rate of diffusion.

Question 9

How do substances move by diffusion?

Answer 9

From an area of high concentration to an area of low concentration, down the concentration gradient

Question 10

How are the leaves adapted to their role?

Answer 10

• Stomate are tiny openings that predominantly cover the lower side of the leaf, allowing air to circulate inside the leaf, which decreases diffusion distance
• The lower layer of the leaf is made from spongy mesophyll cells which allow air to circulate inside the leaf

Question 11

What is the role of the roots in plants?

Answer 11

To absorb water and mineral ions from the soil and anchor the plant

Question 12

What diffuses into the cell?

Answer 12

Oxygen, for aerobic respiration

Question 13

What kind of membrane does osmosis require?

Answer 13

A selective permeable membrane

Question 14

What kind of membrane does active transport require?

Answer 14

A selectively permeable membrane

Question 15

What is a solvent?

Answer 15

The liquid a solid is put into

Question 16

What is the role of gills in fish?

Answer 16

Gas exchange between water flowing through the gills and the blood, to supply cells with oxygen for aerobic respiration and to remove the waste product carbon dioxide

Question 17

What substances can move by active transport?

Answer 17

Any substances

Question 18

Is diffusion a passive or an active process?

Answer 18

Passive process, depending on how much kinetic energy the particles have

Question 19

Is osmosis a passive or active process?

Answer 19

A passive process that does not require energy

Question 20

What diffuses out of a cell?

Answer 20

Carbon dioxide, produced by aerobic respiration

Question 21

What are unicellular organisms?

Answer 21

One cell only

Question 22

What is the role of the Small Intestine?

Answer 22

Most absorption of digested food molecules into the bloodstream occurs across the wall of the small intestine

Question 23

How permeable is the cell membrane?

Answer 23

Partially permeable

Question 24

When an object is larger, is the surface area to volume ration bigger or smaller?

Answer 24

Smaller

Question 25

How are the gills adapted to their role?

Answer 25

• Each gill made from lots of smaller plates called filaments, which are also covered in projections called lamellae which increases surface area
• A dense capillary network ensure a good blood supply which flows in the opposite direction to water passing through the gills which maintains a concentration gradient

Question 26

What can move by diffusion?

Answer 26

Small substances, except water

Question 27

What are multicellular organisms?

Answer 27

Made up of many cells

Question 28

How does a concentration gradient affect diffusion?

Answer 28

A great concentration gradient gives rise to a higher rate of diffusion

Question 29

Is active transport an active or a passive process?

Answer 29

It is an active process which requires energy

Question 30

What is a solute?

Answer 30

A solid that is put into a liquid

Question 31

How do substances move by osmosis?

Answer 31

From a high water potential area to a low water potential area down the water potential gradient

Question 32

What substances can move by osmosis?

Answer 32

Water

Question 33

How does surface area affect diffusion?

Answer 33

A higher surface area gives rise to a higher rate of diffusion

Question 34

What adaptations do the roots have?

Answer 34

Highly branched to increase surface area
Surface of roots covered in root hair cells, increasing surface area