[Part 3]- B1-cell structure 🔬

Question 1

State one dissolved substance that moves out of your cells, by diffusion.

Answer 1

• simple sugars such as glucose.

Question 2

What happens to animal cell if it is in a isotonic solution? Explain your answer

Hint: internal

Answer 2

• Nothing, because the concentration of solutes in the solution, is the same as the internal concentration.

Question 3

What happens to animal cell if it is in a hypertonic solution? [concentrated] Explain your answer

Hint: in the cell

Answer 3

• the animal cell becomes shrivelled, because the concentration of solutes in the solution oustide the cell, is higher than the internal concentration.

Question 4

What happens to animal cell if it is in a hypotonic solution? [distilled solution] Explain your answer

Hint: not shrivelled

Answer 4

• if a cell’s in a hypotonic solution, it bursts.
• This is because, the concentration of solutes in the solution outside, of the cell is higher than the internal concentration.

Question 5

How does water move into plant cells?

Answer 5

• water moves into plant cells by osmosis

Question 6

Explain what the process ‘turgor’ means [3]

Hint: osmosis, cytoplasm, build

Answer 6

1) Water moves into plant cells by osmosis and this causes the vacuole to swell

2) This then presses against the cytoplasm of the plant cell wall

3) The pressure builds up until no more water can physically enter the (plant) cell

Question 7

Why do plant cells need tugor pressure?

Answer 7

• Plant cells need tugor pressure, because it makes the plant cells hard and rigid—–> keeps the leaves + stems of plant rigid and firm

Question 8

A plant cell wilts if there is no tugor pressure supporting the plant tissues. Explain why [3]

Hint: hypertonic, firm, pressure

Answer 8

• If the solution that surrounds the plant cell is hypertonic to cell contents, water leaves the plant cell by osmosis.
• Because of this, the plant cells will no longer be firm + swollen. Instead, they become flaccid
• This is because there is no (tugor) pressure on the cell wall, so the plant wilts because tugor can’t support the plant tissues.

Question 9

Fill in the gaps: Active transport is _________ the concentration gradient.

Answer 9

Active transport is against the concentration gradient.

Question 10

During active transport, energy is needed for the active transport system.

This is because, it’s needed to carry a molecule across the membrane, and then return to it’s original position. State where this energy is released [1]

Answer 10

The energy needed from active transport is released during cellular respiration.

Question 11

Cells that are involved in active transport require energy to be produced. But where is this energy released from?

Answer 11

Energy is released by the mitochondria. [from aerobic respiration]

Question 12

Some living organisms cannot exchange materials quickly enough with the outside world, and instead need a transport system.

Give two reasons for this [2]

Hint: waste, molecules can’t reach

Answer 12

• gases + food molecules can no longer reach every cell inside the organism, by simple diffusion.
• metbolic waste can’t be removed fast enough to avoid poisoining to the cells

Question 13

What are four ways in which the effectiveness of an exchange surface can be increased. [4]

Hint: area, path, supply, ventilated

Answer 13

1) having a large surface area

2) having a thin membrane/being thin.

3) having an effecient blood supply

4) being ventilated

Question 14

What’s the key feature of muscle cells? [2]

Answer 14

• muscle cells can contract (get shorter) because, they contain protein fibres.

Question 15

What do protein fibres do ? [3]

Hint: length

Answer 15

• protein fibres can change their length and shorten when a muscle cell contacts- this decreases the length of the cell.

Question 16

What are muscle cells packed with and why? [2]

Answer 16

• muscle cells are packed with mitochondria, to provide (release) energy for muscle contraction.

Question 17

What does the root hair, do for the root hair cell?

Hint: increases what?

Hint #2: dissolved minerals

Answer 17

• the root hair, increase the surface area of the root, so it can absorb water + dissolved minerals more efficiently [meaning osmosis happens at a faster rate]

Question 18

What do root hair cells don’t have?

Answer 18

• root hair cells don’t contain chloroplasts, because they’re underground.

Question 19

Where are xylem cells found

Hint: stem, forming tubes

Answer 19

• Xylem cells are found in the plant stem, forming long tubes.
• these tubes carry water + dissolved minerals from the roots, to the leaves.

Question 20

What’s a feature of xylem cells? [2]

Hint: 💀

Answer 20

• xylem cells have thick walls containing lignin
• ; since the cells walls are sealed with lignin, this causes the xylem cell to die.

Question 21

What’s a second feature of xylem cells?

Hint: end walls

Answer 21

• the end walls between the cells have completely broken down.
• which means the cells now form a long tube- so water + dissolved minerals can flow easily.

Question 22

What’s a third feature of xylem cells?

Hint: internal structures- why?

Answer 22

• xylem cells have no internal structures such as: no nucleus, cytoplasm, vacuole or chloroplasts- making it easier for water + minerals to flow.

Question 23

What else can you tell me phloem vessel cells? [3]

Hint: sieve plates

Answer 23

• phloem vessel cells have no nucleus + and only a limited cytoplasm
• The end walls of the vessel cells have pores called sieve plates
• both of these features allow dissolved sugars, to move through the cell interior.

Question 23

What can you tell me phloem vessel cells?

Hint: what do the end wall of vessel cells have?

Answer 23

• phloem vessel cells have no nucleus + and only a limited cytoplasm
• The end walls of the vessel cells have pores called sieve plates- both of these features

Question 24

Why do phloem cells have a companion cell? [3]

Hint: not a lot of mitochondria- why?

Answer 24

• phloem vessel cells have a very limiting cytoplasm, they haven’t got a lot of mitochondria.
• So each phloem vessel cell, has a companion cell, that is connected by pores.
• Mitochondria in the companion cell, provide/release energy to the phloem vessel cell.

Question 25

What are some disadvantagss of a light microscope?

Hint: limited

Answer 25

• light microscope have a limited magnification, which means that structures inside the nucleus cannot be easily viewed
• they have limited resolution

Question 26

What are some advantages of an electron microscope?

Answer 26

• electron microscopes, have a much greater magnification and resolution, than light microscopes

Question 27

What’s the equation that links magnification, image size and actual size?

Answer 27

Image size= magnification ✖️actual size

Question 28

Explain four ways in which the effectiveness of an exchange surface can be increased. [4]

Hint: gas exchange is more efficient, mantain a…, steep diffusion gradient, exchange can take place

Answer 28

1) having a large surface area, over which exchange can take place

2) having a thin membrane/being thin to provide a short diffusion path

3) having an efficient blood supply- to move diffusing susbtances away from the exchange surface, + to mantain a steep diffusion gradient.

4) being ventilated- in animals, this makes gas exchange more effecient because it mantains steep concentration gradients.