B6 Plant Structures and their Functions

Question 1

Define

biomass.

Answer 1

the mass of living biological organisms in a given area or ecosystem at a given time

Question 2

What is the order of labels in a food chain?

Answer 2

producer - primary consumer - secondary consumer - tertiary consumer - quaternary consumer

Question 3

What is the equation for

photosynthesis?

Answer 3

… carbon dioxide + water …
…………………….|…………………….
light (energy) | chlorophyll
…………………….↓…………………….
…….. glucose + oxygen ………

(6CO2 + 6H2O -> C6H12O6 + 6O2)

Question 4

What are plants’

uses of glucose?

Answer 4

• to make cellulose, the main structural material in cell walls
• to store energy as starch or sucrose
• to make fats & oils
• for growth, repair and replacement of damaged parts
• as an immediate energy source for respiration

Question 5

What is the

structure of a leaf?

(from top to bottom)

Answer 5

waxy cuticle
upper epidermis
pallisade mesophyll cells
spongy mesophyll cells
lower epidermis/guard cells

Question 6

What are

stomata?

(and what do they do?)

Answer 6

holes/pores in the underside of a leaf that allow for gas exchange

Question 7

What is

phloem?

(and what does it do?)

Answer 7

a tissue which carries sugars from a leaf

Question 8

What are

guard cells?

(and what do they do?)

Answer 8

cells at the bottom of a leaf which control the size of the stomata

(to control water loss)

Question 9

What are

pallisade cells?

(and what do they do?)

Answer 9

cells which contain many chloroplasts and carry out most of the photosynthesis in a leaf

Question 10

What is

xylem?

(and what does it do?)

Answer 10

the tissue which carries water to a leaf

Question 11

What are

spongy mesophyll?

Answer 11

cells with air pockets which carry out a bit of photosynthesis

Question 12

What is the

waxy cuticle?

(and what does it do?)

Answer 12

a waterproof layer at the top of leaves which stops water from evaporating from the cells

Question 13

What conditions limit photosynthesis?

Answer 13

• carbon dioxide levels
• light intensity
• temperature

Question 14

What is the inverse square law?

(calculating new light intensity)

Answer 14

new light intensity = original light intensity x (original distance)^2 / (new distance)^2

(light intensity is measured in lux)

Question 15

What are roots used for?

Answer 15

• extracting water
• extracting mineral ions
• anchorage

Question 16

Describe a

turgid plant cell.

Answer 16

• full of water
• gives support
• vacuole is filling all of the space and pushing against the cell wall

Question 17

Describe a

flaccid plant cell.

Answer 17

• starting to lose water
• gives some support
• vacuole is much smaller and taking up less space

Question 18

Describe a

plasmolysed plant cell.

Answer 18

• very dehydrated cell
• gives little support
• cell membrane + cytoplasm far from cell wall in most places

Question 19

Define

osmosis.

Answer 19

the net movement of water across a partially permeable membrane from a high water potential to a low water potential

Question 20

How are root hair cells adapted to absorb water and mineral ions?

Answer 20

• large surface area
• thin cell walls
• large permanent vacuole containing sugars
• many mitchondria which release energy for active transport

Question 21

What are the characteristics of

xylem?

Answer 21

• transports water and minerals
• no end walls between cells
• one-way only
• outer cells are not living
• movement is upwards
• carries out transpiration

Question 22

What are the characteristics of

phloem?

Answer 22

• transports organic molecules
• end walls between cells
• two-way movement
• cells are living but need support
• carries out translocation

Question 23

What is the

structure of xylem?

Answer 23

• composed of dead cells
• no top and bottom cell walls
• cell walls are thickened and contain rings of lignin
• forms continuous xylem vessels which are rigid
• prevents bursting or collapsing under pressure
• supports the plant
• tiny pores called pits connect adjacent xylem vessels

Question 24

What is the

transpiration stream?

Answer 24

the movement of water upwards through the plant xylem

Question 25

What is

transpiration?

Answer 25

the flow of water into a root, up the stem and then out of the leaves via evaporation then diffusion

Question 26

What is

water’s journey to the xylem?

Answer 26

1. Water enters the root hairs by osmosis.
2. Water passes across the root, from cell to cell by osmosis. It also seeps between the cells.
3. Water is drawn up the xylem vessels because transpiration is constantly removing water from the top of them.

Question 27

What factors change the rate of transpiration?

Answer 27

• temperature
• humidity
• wind
• light intensity