Growth In Plants

Question 1

What kind of tissues are the growing roots and shoots in plants?

Answer 1

Meristems

Question 2

Describe meristems:

Answer 2

A region of plant tissue consisting of undifferentiated cells that are capable of continuous division

Question 3

How do meristems divide?

Answer 3

Rapidly by mitosis

Question 4

What are stem cells?

Answer 4

Cells that can differentiate to become any type of specialised cell

Question 5

What happens to many stem cells after mitosis?

Answer 5

They become specialised

Question 6

Where are meristems found?

Answer 6

Where growth takes place in a plant
Eg. Roots and shoots

Question 7

Describe the function of a xylem vessel:

Answer 7

Responsible for transporting water and minerals from the roots to other parts of the plant

Question 8

What is a xylem vessel?

Answer 8

Long tube formed from dead xylem cells

Question 9

Where is the zone of division?

Answer 9

Area closest to the tip of the shoot

Question 10

What happens in the zone of division?

Answer 10

Cells are actively dividing, producing new cells by mitosis

Question 11

What happens in the zone of elongation?

Answer 11

Cells begin to elongate or get larger by pushing the shoot tip upwards and contributing to the lengthening of the plant

Question 12

What happens at the zone of differentiation?

Answer 12

Start to specialise into various cell types, differentiating tissues such as xylem, phloem and other cells depending on the cells needs

Question 13

What is the xylem tissue made of?

Answer 13

Long tube formed from many dead xylem cells

Question 14

Give 4 adaptations of xylem:

Answer 14

1. Thickened walls - carry water under pressure
2. Tiny pores - allow water and minerals to enter and leave the vessel
3. No cytoplasm - vessel is empty
4. Lots of cell walls - to form a tube

Question 15

Name 2 adaptation of a root hair cell:

Answer 15

1. Many hairs - increase the surface area which increases rate of mineral and water absorption from the soil
2. Thin walls - make the diffusion of minerals into cells more efficient

Question 16

State the equation used to measure percentage growth:

Answer 16

Final value - Starting value
————————————- X100
Starting value

Question 17

Why can measuring the change in mass of a plant over time can be used to measure the plant’s growth?

Answer 17

• Reflects the overall increase in cell numbers + cell size
• As plant accumulates more biomass, its mass increases, providing a quantitative measure of growth.

Question 18

What is the function of guard cells?

Answer 18

In the day time (photosynthesis), stomata is open to enable gas exchange as the guard cells have taken water in by osmosis are are turgid (stiff/immovable)
At night (no photosynthesis), the stomata closes to prevent water loss from leaves. This is because the guard cells have lost water by osmosis and are flaccid (Flexible/shrunken)

Question 19

How are guard cells adapted to their function? (3)

Answer 19

Bean shaped
Chloroplasts for photosynthesis
Can change shape by swelling or shrinking in response to the water pressure inside of them, thus opening and closing the stomata as necessary to maintain the plants water balance

Question 20

How are palisade cells adapted to their function? (2)

Answer 20

Lots of chloroplasts which absorb light for photosynthesis
Brick shaped so many can fit into the top layer of the leaf

Question 21

Describe the following feature of a xylem vessel that are not found in other plant cells:
Lignified walls

Answer 21

Thickened cells walls of the xylem which are infused with lignin to provide strength and structural support

Question 22

Describe the following feature of a xylem vessel that are not found in other plant cells:
Pits

Answer 22

Small openings or depressions in the wall of the xylem vessel, which facilitates the lateral movement of water between vessels

Question 23

Describe the following feature of a xylem vessel that are not found in other plant cells:
Hollow lumen

Answer 23

Hollow interior part of the xylem vessel which is a characteristic feature allowing the passage of water and minerals

Question 24

Describe the following feature of a xylem vessel that are not found in other plant cells:
End wall/ Perforation plate

Answer 24

Found at the end of the xylem vessel with open end walls or large openings, these allow for the vertical flow of water from one vessel to the next

Question 25

State 4 features of a xylem vessel that are not found in other plant cells:

Answer 25

1. Lignified walls
2. Hollow lumen
3. End wall/ Perforation plate
4. Pits