Paper 2: Section 6- Plant Structures and Their Functions

Question 1

What is photosynthesis?

Answer 1

The process by which plants or algae create glucose using light energy (absorbed by chlorophyll) H20 and C02.

Question 2

What is the word equation for photosynthesis?

Answer 2

Carbon dioxide + water –(LIGHT)-> Glucose + Oxygen

Question 3

What is the symbol equation for photosynthesis?

Answer 3

6C0^2 + 6H^20 –(LIGHT)-> C^6H^120612 + 60^2

Question 4

Is photosynthesis an endothermic or exothermic reaction? Why?

Answer 4

Endothermic- energy is taken in during a reaction.

Question 5

Describe photosynthetic organisms as the main producers of food and therefore biomass?

Answer 5

Photosynthetic organisms make their own food though photosynthesis and are a source of food for other organisms. Thee glucose made in photosynthesis makes-up the organisms biomass.

Question 6

What 4 main limiting factors that affect photosynthesis?

Answer 6

. Light
. C02 concentration
. Temperature
. Availability of water

Question 7

Explain the interactions of light intensity, C02 concentration, availability of water and temperature in limiting the rate of photosynthesis.

Answer 7

. As the concentration of C02 and the volume of water increases, so does the rate of photosynthesis.
. Similarly, if there isn’t enough light a plant can’t photosynthesis or if it isn’t optimum temperature the rate can’t be sped up.

Question 8

What is the inverse square law and how is it written?

Answer 8

Inverse square law- Light intensity decreases in proportion to the square of the distance.
Light intensity ∝ 1/ distance (d)^2

Question 9

How are the structures of the xylem adapted to their functions?

Answer 9

Lignified dead cells- allow the xylem to withstand pressure changes as the xylem moves water through the plant and transfers minerals.

Question 10

What does the xylem transport and in what direction? What type of process is this?

Answer 10

The transport is a physical process where water and minerals move upwards from the roots to the leaves.

Question 11

Transpiration is the ____ of water from ______ by ___________ through the ______.

Answer 11

1. loss
2. leaves
3. evaporation
4. stomata

Question 12

What are the purposes of transpiration in photosynthesis?

Answer 12

. Provides water for photosynthesis
. Transports mineral ions/ water from the roots to leaves
. Cools down the leaf
. Provides water to keep the cell turgid (which supports non-woody plants)

Question 13

How do you calculate the rate of transpiration?

Answer 13

Rate of transpiration= distance moved by air bubble (m)/ time (min)

Question 14

How are the structures of the phloem adapted to their functions?

Answer 14

Living cells:
Sieve tubes- they have no nucleus and each tube has a perforated end to connect the cell to another for easy transport of sucrose.
Companion cells- one or more are attached to each sieve cell to provide energy for transport.

Question 15

What does the phloem transport and in what direction? What type of process is this?

Answer 15

The phloem transports food substances upwards and downwards from leaves to the rest of the plant (and from stores like roots). This requires energy.

Question 16

Translocation is the transport of _________ materials within a _____.

Answer 16

1. dissolved
2. plant

Question 17

What part does translocation play once glucose from photosynthesis is made into sucrose?

Answer 17

. Translocation transports sucrose from the source to the sink.
. Later the sucrose can be converted back into glucose for respiration.

Question 18

What part does translocation play once glucose from photosynthesis is made into sucrose?

Answer 18

. Translocation transports sucrose from the source to the sink.
. Later the sucrose can be converted back into glucose for respiration.

Question 19

What is the function of the stomata in transportin water and mineral ions?

Answer 19

The stomata lets in C02, which is controlled by the guard cells, which allows water to evaporate and diffuse off the leaf (aka transpiration).

Question 20

What is gas exchange?

Answer 20

The movement of C02 and 02 through a leaf in opposite directions.

Question 21

How is the structure of a leaf is adapted for photosynthesis and gas exchange?

Answer 21

. Large surface area- to absorb more light.
. Thin/ transparent epidermis- allows more light to reach the palaside cells.
. Waxy cuticle- the wax protects the leaf from infestation and prevents water loss without blocking light.
. Palaside mesophyll- absorbs more light and increases the rate of photosynthesis.
. Spongy mesophyll- air spaces allow gases to diffuse through the leaf.

Question 22

What are the 4 main environmental factors that effect the rate of water uptake?

Answer 22

1. Light intensity
2. Air movement
3. Temperature
4. Humidity

Question 23

What are the effects of environmental factors on the rate of water uptake?

Answer 23

When there is a high condition of air movement, light intensity, and temperature the effect on the rate of water uptake is more because it increases water loss.
However, in a high condition of humidity, the effect on the rate of water uptake is less.

Question 24

How are plants adapted to survive extreme environments?

Answer 24

Smaller size leaf- minimise surface so there is less water loss in a hot area.
Shape- to fit an area, to protect, or to collect as much water as possible.
Thick and waxier cuticle- reduces water loss by evaporation.
Deep root systems- collect more water.
Less stomata- reduce water loss by transpiration.