B5 - Plant Nutrition

Question 1

Define photosynthesis.

Answer 1

The process by which plants manufacture carbohydrates from raw materials using energy from sunlight.

Question 2

What is the word equation for photosynthesis?

Answer 2

carbon dioxide + water -> glucose + oxygen

Question 3

State the balanced equation for photosynthesis.

Answer 3

6CO2 + 6H20 –light/chlorophyll–> C6H12O6 + 6O2

Question 4

What is the role of glucose?

Answer 4

used in respiration

Question 5

What is the role of sucrose?

Answer 5

stored in fruit and nectar to attract insects for pollination

Question 6

What is the role of starch?

Answer 6

food store in chloroplasts OR energy

Question 7

What is the role of cellulose?

Answer 7

to form strong cell walls

Question 8

What is the role of fats and oils?

Answer 8

foot store and growth

Question 9

What is the role of proteins?

Answer 9

growth and repair

Question 10

List the five main ways plants use glucose.

Answer 10

1. For respiration
2. Making cellulose
3. Making amino acids
4. Stored as fat or oils
5. Stored as starch

Question 11

What is an energy transducer?

Answer 11

Organelles that can transform one source of energy into another.

Question 12

Name an energy transducer.

Answer 12

Chloroplasts.

Question 13

What is the pigment that absorbs light energy?

Answer 13

Chlorophyll.

Question 14

What is the role of chloroplasts?

Answer 14

To act as energy transducers, converting light energy into chemical energy.

Question 15

Where does photosynthesis happen? [2]

Answer 15

The leaves of the plant. Specifically, chloroplasts.

Question 16

What does autotrophic mean?

Answer 16

Self-feeding.

Question 17

How do you test a leaf for starch? [4]

Answer 17

1) Hold the leaf in boiling water with tweezers. This stops any chemical reactions happening inside the leaf and also breaks down cell walls.
2) Put the leaf in a boiling tube with some ethanol and put it in an electric water-bath until it boils. This gets rid of any chlorophyll and makes the leaf an almost white colour.
3) Dip the leaf in warm water to soften the brittle leaf and allow penetration by iodine solution.
4) Place the leaf on a white tile and add a few drops of iodine solution. If starch is present the leaf will turn blue-black.

Question 18

What is a variegated leaf?

Answer 18

A leaf that has different colors. E.g. green (chlorophyll) and white (no chlorophyll)

Question 19

List the chemical elements in a carbohydrate.

Answer 19

Carbon, Hydrogen, Oxygen.

Question 20

What is the test for starch?

Answer 20

Iodine solution. If starch is present it will turn blue-black.

Question 21

Where are most of the chloroplasts found in the leaf?

Answer 21

The palisade mesophyll layer.

Question 22

What are the holes that allow diffusion of carbon-dioxide and oxygen in and out of the leaf called?

Answer 22

Stomata. They are mainly present in the lower epidermis. They close in the dark.

Question 23

What is the top layer of the leaf and what is its function?

Answer 23

The waxy cuticle. It reduces water loss.

Question 24

What is the layer under the waxy cuticle and what is its function?

Answer 24

The upper epidermis. It is usually one cell thick and transparent to allow free passafe of light. It prevents the entry of disease-causing organisms such as bacteria and fungi.

Question 25

What is the layer where the chloroplasts are?

Answer 25

Palisade Mesophyll. Tall, thin cells arranged in columns and separated by narrow air spaces. Contain many chloroplasts and dense packing of cells ensures maximum absoption of light energy.

Question 26

What is the vein in the plant?

Answer 26

Transport system that contains xylem and phloem. Xylem is on top.

Question 27

What layer is the vein found in?

Answer 27

Spongy Mesophyll. Loosely packed cells covered in a thin layer of water. Lots of air space enable diffusion of gases through the leaf. Air spaces are saturated with water so water diffuses out the leaf.

Question 28

What happens to the guard cells when the plant has plenty of water?

Answer 28

They become turgid and swell causing the cell wall to curve and open the stomata.

Question 29

Name the two mineral ions that plants need.

Answer 29

Nitrate ions and Magnesium ions.

Question 30

What are nitrate ions needed for?

Answer 30

Making amino acids and proteins, which are needed for cell growth.

Question 31

What happens if a plant has a nitrate ion deficiency?

Answer 31

It will be stunted and older leaves will turn yellow.

Question 32

What are magnesium ions needed for?

Answer 32

Needed to make chlorophyll.

Question 33

What happens if a plant has a magnesium ion deficiency?

Answer 33

It won’t make enough chlorophyll and will have chlorosis (the leaves of the plant will turn yellow). Also have stunted growth.

Question 34

Where do minerals enter a plant?

Answer 34

Through the root hair cells.

Question 35

Define limiting factor.

Answer 35

Something present in the environment in such short supply that it restricts life processes.

Question 36

Name three limiting factors that affect photosynthesis.

Answer 36

Light intensity
Temperature
CO2 concentration

Question 37

How does light intensity affect photosynthesis?

Answer 37

Increases light intensity increases the rate of photosynthesis up to a certain point where it will level off.

Question 38

How does temperature affect photosynthesis?

Answer 38

Optimum temp. Like enzymes if it gets to high the enzymes will denature and the rate of photosynthesis will decrease.

Question 39

What five things do you need to include when planning an investigation?

Answer 39

Independent variable
Dependent variable
Control variables
Reliability
Safety