B2 - Scaling Up

Question 1

What is diffusion?

Answer 1

The net (overall) movement of particles from a region of high concentration to a region of low concentration.

Question 2

Do the particles in diffusion move down or against a concentration gradient?

Answer 2

Down

Question 3

What factors affect the rate of diffusion?

Answer 3

1) distance
2) concentration gradient
3) surface area

Question 4

How do you increase the rate of diffusion?

Answer 4

1) decrease the distance the particles need to move
2) increase the concentration gradient
3) increase the surface area

Question 5

What is osmosis?

Answer 5

The diffusion of water molecules across a selectively permeable membrane

Question 6

What is the water potential?

Answer 6

The concentration of free water molecules

Question 7

What type of water has the highest possible water potential?

Answer 7

Pure water

Question 8

Does osmosis move down or against a concentration gradient?

Answer 8

Down

Question 9

What happens to a plant cell if the surroundings are a less concentrated solution than cell contents?

Answer 9

1) it takes up water by osmosis
2) the pressure in the cell increases
3) the cell becomes firm or turgid

Question 10

What happens to a plant cell if the surroundings have the same concentration as the cell contents?

Answer 10

1) there is no net movement of water

2) the cell remains the same

Question 11

What happens to a plant cell if the surroundings are a more concentrated solution than cell contents?

Answer 11

1) it loses water by osmosis
2) the pressure in the cell decreases
3) the cell becomes flaccid (soft)
4) the cell contents collapse away from the cell wall
5) the cell becomes plasmolysed

Question 12

What happens to an animal cell if the surroundings are a less concentrated solution than cell contents?

Answer 12

1) it takes up water
2) swells and may burst
3) undergoes lysis

Question 13

What happens to an animal cell if the surroundings have the same concentration as cell contents?

Answer 13

1) there is no net movement of water

2) the cell remains the same

Question 14

What happens to an animal cell if the surroundings are a more concentrated solution than cell contents?

Answer 14

1) loses water by osmosis

2) cell becomes crenated (it crinkles)

Question 15

Does active transport move down or against a concentration gradient?

Answer 15

Against

Question 16

What are the three key features of active transport?

Answer 16

1) particles are transported (pumped) against a concentration gradient
2) ATP is required
3) the process makes use of carrier proteins in the cell membrane

Question 17

What do cells that carry out a lot of active transport contain many of?

Answer 17

Mitochondria

Question 18

What does the rate of active transport depend on?

Answer 18

The rate of respiration to produce the required ATP

Question 19

What do carrier proteins do?

Answer 19

Transports molecules into the cell

Question 20

When is active transport used?

Answer 20

Whenever a substance needs to be moved against a concentration gradient

Question 21

Give examples of when active transport is used.

Answer 21

1) digestion - in the small intestine carbohydrates are broken down into glucose. Glucose is actively transported into the bloodstream through the villi
2) nerve cells - a carrier protein actively pumps sodium ions out of the cell. At the same time potassium ions are pumped back in. The sodium potassium pump plays an important role in creating nerve impulses
3) plants - plants use active transport to take in minerals from the soil

Question 22

Why do body cells divide?

Answer 22

1) to replace worn out cells
2) to repair damaged tissue
3) to enable the organism to increase in size

Question 23

What is mitosis?

Answer 23

The process in which body cells divide

Question 24

What does mitosis produce?

Answer 24

Two identical daughter cells

Question 25

What is the process of cell growth and division called?

Answer 25

Cell cycle

Question 26

What are the four stages in the cell cycle?

Answer 26

1) DNA replication
2) movement of chromosomes
3) cytokenesis
4) growth of the daughter cells

Question 27

How is DNA replicated?

Answer 27

1) the DNA molecule ‘unzips’ forming two separate strands
2) the DNA bases on each strand are exposed
3) free nucleotides in the nucleus line up against each of the strand following the rule of complementary base pairing
4) this forms DNA base pairs
5) when the whole strand is complete, there are two identical molecules of DNA

Question 28

How do chromosomes move?

Answer 28

1) the chromosomes line up across the centre of the cell
2) the two identical copies of each chromosome, formed when the DNA replicated, separate and move to opposite ends of the cell
3) each end now contains a full set of identical chromsosomes
4) two new nuclei then form

Question 29

How are sperm cells specialised?

Answer 29

To transfer genetic material from to the ovum (egg)

Question 30

What do the flagellums on sperm cells do?

Answer 30

Whips from side to side to propel the sperm to the ovum

Question 31

Why do sperm cells have lots of mitochondria?

Answer 31

Respiration occurs in mitochondria, and the reactions of respiration transfer energy from chemical stores so that the flagellum can move

Question 32

What do the acrosome in sperm cells do?

Answer 32

Stores digestive enzymes, which break down the outer layers of the ovum to allow the sperm to transfer and incorporate its genetic material

Question 33

How are fat cells specialised?

Answer 33

To store fat

Question 34

How are red blood cells specialised?

Answer 34

To transport oxygen around the body

Question 35

What are the three main adaptations of re blood cells?

Answer 35

1) biconcave discs - they are pushed in on both sides to form a biconcave shape, which increases the surface are to volume ratio, speeding up the diffusion of oxygen into the cell and carbon dioxide out of the cell
2) packed full of haemoglobin - this protein binds to oxygen to form oxyhaemoglobin, which is bright red
3) no nucleus - this means that there is space to contain more haemoglobin molecules

Question 36

What do goblet cells produce?

Answer 36

Sticky mucus