2.5.2 Factors Affecting Photosynthesis

Question 1

Plants do not have unlimited supplies of their raw materials so their rate of photosynthesis is limited by, what?

Answer 1

by whatever factor is the lowest at that time

Question 2

What is a limiting factor defined as?

Answer 2

a limiting factor can be defined as something present in the environment in such short supply that it restricts life processes

Question 3

In photosynthesis, what are the 3 main limiting factors

Answer 3

Temperature
Light intensity
Carbon dioxide concentration

Question 4

Although water is necessary for photosynthesis why is it not considered a limiting factor

Answer 4

it is not considered a limiting factor as the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis

Question 5

The number of chloroplasts or the amount of chlorophyll in the chloroplasts can affect what?

Answer 5

the rate of photosynthesis

Question 6

How does temperature affect photosynthesis

Answer 6

The temperature of the environment affects how much kinetic energy all particles have – so temperature affects the speed at which carbon dioxide and water move through a plant

Question 7

In photosynthesis, how does a lower temperature affect it?

Answer 7

The lower the temperature, the less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time

Question 8

In photosynthesis, how does increasing temperature affect it?

Answer 8

Increasing temperature increases the kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products

Question 9

What is a repercussion of high temperature

Answer 9

enzymes that control the processes of photosynthesis can be denatured – this reduces the overall rate of photosynthesis

Question 10

How does The intensity of the light affect photosynthesis

Answer 10

The intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis

Question 11

The more light a plant receives, does photosynthesis occur faster, or slower?

Answer 11

The more light a plant receives, the faster the rate of photosynthesis

Question 12

Name one of the raw materials needed for photosynthesis

Answer 12

Carbon dioxide is one of the raw materials required for photosynthesis

Question 13

the more carbon dioxide that is present, what happens?

Answer 13

the faster the reaction can occur

This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 14

Do chloroplasts affect the rate of photosynthesis?

Answer 14

The number of chloroplasts (as they contain the pigment chlorophyll which absorbs light energy for photosynthesis) will affect the rate of photosynthesis

Question 15

The amount of chlorophyll can be affected by, what?

Answer 15

Diseases (such as tobacco mosaic virus)
Lack of nutrients (such as magnesium)
Loss of leaves (fewer leaves means fewer chloroplasts)

Question 16

(Leaf Structure) What is the description of Wax Cuticle

Answer 16

Protective Layer on top of the leaf prevents water from evaporating

Question 17

(Leaf Structure) What is the description of the Upper Epidermis

Answer 17

Thin and transparent to allow light to enter the palisade mesophyll layer underneath it

Question 18

(Leaf Structure) What is the description of Palisade Mesophyll

Answer 18

Column shaped cells tightly packed with chloroplasts to absorb more light, maximizing photosynthesis

Question 19

(Leaf Structure) What is the description of Spongy Mesophyll

Answer 19

Contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases (mainly carbon dioxide)

Question 20

(Leaf Structure) What is the description of Lower Epidermis

Answer 20

Contains guard cells and stomata

Question 21

(Leaf Structure) What is the description of Guard Cell

Answer 21

Absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out

Question 22

(Leaf Structure) What is the description of Stomata

Answer 22

Where gas exchange takes place; Opens during the day, closes during the night. Evaporation of water also takes place from here, in most plants, found in much greater concentration on the underside of the leaf to reduce water loss.

Question 23

(Leaf Structure) What is the description of Vascular Bundle

Answer 23

Contains xylem and phloem to transport substances to and from the leaf.

Question 24

(Leaf Structure) What is the description of Xylem

Answer 24

Transports water into the leaf for Mesophyll cells to use in photosynthesis and for transpiration from stomata

Question 25

(Leaf Structure) What is the description of Phloem

Answer 25

Transports sucrose and amino acids around the plant

Question 26

Photosynthesis provides a source of carbohydrates, but plants contain and require many other types of biological molecules, such as:

Answer 26

such as proteins, lipids and nucleic acid (DNA)

Question 27

Carbohydrates contain the elements:

Answer 27

carbon, hydrogen and oxygen

Question 28

What are the 2 fundamental mineral ions required by plants?

Answer 28

nitrogen and magnesium, without a source of these elements, plants cannot photosynthesise or grow properly

Question 29

Plants obtain these elements in the form of, what?

Answer 29

mineral ions actively absorbed from the soil by root hair cells

Question 30

Mineral’ is a term used to describe, what?

Answer 30

any naturally occurring inorganic substance

Question 31

What is the function of Magnesium and deficiency

Answer 31

Function: Magnesium is needed to make chlorophyll

Deficiency: Causes yellowing between the veins of leaves (chlorosis)

Question 32

What is the function and deficiency of Nitrate

Answer 32

Function: Nitrates are a source of nitrogen needed to make amino acids(to build protein)

Deficiency: Causes stunted growth and yellowing of leaves