Key Area 1

Question 1

What is food security

Answer 1

The ability of human populations to access food of sufficient quality and quantity

Question 2

What does the increase in human population and concern for food security lead to

Answer 2

A demand for an increase in food production

Question 3

What does agricultural production depend on

Answer 3

Factors that control photosynthesis and plant growth

Question 4

What is a cultivar

Answer 4

Cultivated variety- a plant or group of plants selected for desirable traits

Question 5

What are the 3 fates of light striking a leaf

Answer 5

Absorption, transmission and reflection

Question 6

Give examples of plant crops

Answer 6

Cereals, potatoes, roots and legumes

Question 7

Why do livestock produce less food per unit than plant crops

Answer 7

Energy is lost by undigested food and waste, maintaining body temperature, movement. The shorter food chain the more energy efficient it is

Question 8

What is photosynthesis?

Answer 8

The process by which green plants convert light energy into chemical energy in molecules of glucose.

Question 9

What are the raw materials needed for photosynthesis?

Answer 9

Carbon dioxide and water.

Question 10

What is the by-product of photosynthesis?

Answer 10

Oxygen.

Question 11

What is the main pigment involved in photosynthesis?

Answer 11

Chlorophyll.

Question 12

What is the spectrum of visible light made up of?

Answer 12

Different colours, each with a different wavelength.

Question 13

How does light interact with leaves?

Answer 13

Light may be absorbed, transmitted, or reflected.

Question 14

What is a pigment?

Answer 14

A substance that absorbs and reflects visible light.

Question 15

Name the main types of plant pigments.

Answer 15

• Chlorophyll a
• Chlorophyll b
• Carotene
• Xanthophyll

Question 16

What technique is used to separate pigments?

Answer 16

Thin-layer chromatography.

Question 17

Which wavelengths of light does chlorophyll primarily absorb?

Answer 17

• Blue
• Red

Question 18

Fill in the blank: The colour of the pigment is the light that is not _______.

Answer 18

absorbed.

Question 19

True or False: Chlorophyll absorbs green light.

Answer 19

False.

Question 20

What wavelengths of light do chlorophyll a and b primarily absorb?

Answer 20

Mainly blue and red light.

Question 21

What role do carotenoids play in photosynthesis?

Answer 21

They absorb energy from other regions of the spectrum and pass it on to chlorophyll.

Question 22

How is the absorption spectrum of pigments measured?

Answer 22

Using a spectrometer.

Question 23

What does an action spectrum show?

Answer 23

The extent to which different wavelengths of light are used for photosynthesis.

Question 24

What is the relationship between absorption and action spectra?

Answer 24

They reveal a close match, indicating the crucial role of leaf pigments in photosynthesis.

Question 25

What are the two stages of photosynthesis?

Answer 25

* Light-dependent stage * Carbon fixation (Calvin cycle)

Question 26

Where do both stages of photosynthesis take place?

Answer 26

In the chloroplasts.

Question 27

Where does carbon fixation occur within the chloroplasts?

Answer 27

In the stroma.

Question 28

Who demonstrated the Hill reaction and in what year?

Answer 28

Robert Hill in 1939.

Question 29

What is photolysis?

Answer 29

The breakdown of water into hydrogen and oxygen.

Question 30

What happens to DCPIP in the presence of light and hydrogen?

Answer 30

It loses its color and becomes colorless.

Question 31

What is produced during the light reactions of photosynthesis?

Answer 31

Oxygen.

Question 33

What is the initial process of energy capture in photosynthesis?

Answer 33

Light energy is absorbed, exciting electrons in the pigment molecule. ## Footnote This is the first step in the light-dependent reactions of photosynthesis.

Question 34

What happens to the excited electrons in the pigment molecule?

Answer 34

Electrons are transferred along an electron transport chain. ## Footnote This transfer releases energy used in various processes.

Question 35

What is photolysis in the context of photosynthesis?

Answer 35

The splitting of water into oxygen and hydrogen. ## Footnote This process occurs during the light-dependent reactions.

Question 36

What enzyme generates ATP during photosynthesis?

Answer 36

ATP synthase. ## Footnote It uses the energy released from the flow of electrons.

Question 37

What is the primary product of the light-dependent stage of photosynthesis?

Answer 37

ATP and NADPH. ## Footnote These products are essential for the Calvin cycle.

Question 38

Who first described the Calvin cycle?

Answer 38

Melvin Calvin. ## Footnote He studied the reactions converting carbon dioxide into sugar.

Question 39

Where does the Calvin cycle take place?

Answer 39

In the stroma of the chloroplast. ## Footnote This is the second stage of photosynthesis.

Question 40

What is the role of RuBisCO in the Calvin cycle?

Answer 40

It catalyzes the reaction between carbon dioxide and ribulose bisphosphate (RuBP). ## Footnote RuBisCO is crucial for carbon fixation.

Question 41

What does carbon dioxide combine with in the Calvin cycle?

Answer 41

Ribulose bisphosphate (RuBP). ## Footnote This forms 3-phosphoglycerate (3PG).

Question 42

What does 3-phosphoglycerate (3PG) produce when it combines with hydrogen from NADPH and ATP?

Answer 42

Glyceraldehyde-3-phosphate (G3P). ## Footnote G3P is a key intermediate in the Calvin cycle.

Question 43

What are the two main uses of glyceraldehyde-3-phosphate (G3P)?

Answer 43

* Regenerate RuBP * Synthesize glucose (sugar) ## Footnote This allows the Calvin cycle to continue and produce energy storage.

Question 44

What are the primary uses of sugar produced in photosynthesis?

Answer 44

* Respiration * Starch (storage carbohydrate) * Cellulose (structural carbohydrate) * Biosynthetic pathways for DNA, lipids, proteins, and nucleic acids ## Footnote These uses are vital for plant growth and energy.

Question 45

Fill in the blank: The enzyme that catalyzes the conversion of carbon dioxide into sugar is called _______.

Answer 45

RuBisCO ## Footnote RuBisCO is essential for carbon fixation in the Calvin cycle.

Question 46

True or False: Oxygen is released into the atmosphere during the Calvin cycle.

Answer 46

False. ## Footnote Oxygen is released during the light-dependent reactions, not the Calvin cycle.