Food Supply, Plant Growth and Productivity

SQA Higher Biology 2022

Photolysis Photolysis

________ uses the rest of the light energy to split water into hydrogen ions and oxygen.

Photosynthetic Pigments Pigments

________ are chemicals found within the chloroplasts which absorb light energy in order to generate ATP (see below)

enzyme RuBisCO

The ________ fixes carbon dioxide by attaching it to ribulose bisphosphate (RuBP)

BIOLOGY FOOD SUPPLY

________, PLANT GROWTH AND PRODUCTIVITY Photosynthesis Photosynthesis is the process by which green plants trap light energy and use it to make carbohydrates.

NADP

The oxygen is evolved (released into the atmosphere) and the hydrogen ions are transferred to the co- enzyme ________ to form NADPH and is then transferred to the Calvin Cycle along with the ATP from earlier.

Glucose Glucose

________ can be used as a respiratory substrate, synthesised into starch or cellulose or passed to other biosynthetic pathways.

Calvin Cycle

The ________ is the temperature- dependent part of photosynthesis.

Absorption and Action Spectrum

________ The absorption spectra shows the wavelength of light that each pigment absorbs.

multiple photosynthetic pigments

Having ________ increases the range of wavelengths of light that the plant can absorb and so increases the level of photosynthesis (wavelength of light is a limiting factor for photosynthesis)

Food production

________ can be increased through factors that control plant growth: ❥ breeding of higher yielding cultivators ❥ use of fertilisers ❥ protect crops from pests, diseases and competition.

Glyceraldehyde 3 phosphate

________ is used to regenerate RuBP and for the synthesis of glucose.

human population

An increase in ________ and concerns for food security leads to a demand for increased food production.

Livestock

________ produce less food per unit area than crop plants due to a loss of energy between trophic levels.

Livestock production

________ is often possible in habitats unsuitable for growing crops.

Light energy

________ thats not absorbed is transmitted or reflected.

Carbon Fixation

________ (Calvin Cycle) The carbon fixation stage is a series of enzyme- controlled reactions which does not require light.

BIOLOGY FOOD SUPPLY

________, PLANT GROWTH AND PRODUCTIVITY Absorbed Light Energy Absorbed light energy excites electrons in the pigment molecule.

Food production can be increased through factors that control plant growth

❥ breeding of higher yielding cultivators ❥ use of fertilisers ❥ protect crops from pests, diseases and competition

Breeders seek to develop crops with

❥ high nutritional values ❥ resistance to pests and diseases ❥ physical characteristics suited to rearing and harvesting as well as those that can thrive in particular environmental conditions

The principal pigments are chlorophyll a and b, but plants also contain carotenoids

they extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis

What is food security?

Food security is the ability of human populations to access food of sufficient quality and quantity.

What does an increase in human population and concerns for food security lead to?

An increase in human population and concerns for food security leads to a demand for increased food production.

What must food production be?

Food production must be sustainable and not degrade the natural resources on which agriculture depends.

How can food production be increased? Give examples.

Food production can be increased through factors that control plant growth such as the breeding of higher yielding cultivars, the use of fertilisers and protecting crops from pests, diseases and competition.

What is the area to grow crops?

The area to grow crops is limited.

Give some examples of plant crops grown.

Examples of plant crops grown include cereals, potatoes, roots and legumes.

What do breeders seek to develop crops with?

Breeders seek to develop crops with high nutritional values, resistance to pests and diseases and physical characteristics suited to rearing and harvesting as well as those that can thrive in particular environmental conditions.

Compare livestock to crop plants.

Livestock produce less food per unit area than crop plants due to a loss of energy between trophic levels. Livestock production is often possible in habitats unsuitable for growing crops.

What is all food production ultimately dependent on?

Ultimately, all food production, plant or animal, is dependent on factors which control photosynthesis (eg. light availability, available nutrients, water in the soil and competition with other plants).

What is photosynthesis?

Photosynthesis is the process by which green plants trap light energy and use it to make carbohydrates.

What are pigments?

Pigments are chemicals found within the chloroplasts which absorb light energy in order to generate ATP.

What are the three fates of light energy?

Light energy can be absorbed, transmitted or reflected.

What does each photosynthetic pigment do?

Each photosynthetic pigment absorbs different wavelengths of light.

What pigments do plants have?

The principal pigments are chlorophyll a and b, but plants also contain carotenoids.

What do carotenoids do?

They extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis.

What does the absorption spectra show?

The absorption spectra shows the wavelength of light that each pigment absorbs.

What does the action spectra show?

The action spectra shows the relative rate of photosynthesis at different wavelengths of light.

What is the effect of a plant having multiple photosynthetic pigments?

Having multiple photosynthetic pigments increases the range of wavelengths of light that the plant can absorb and so increases the level of photosynthesis.

What is a limiting factor for photosynthesis?

Wavelength of light is a limiting factor for photosynthesis.

What happens to absorbed light energy?

Absorbed light energy excites electrons in the pigment molecule. The transfer of these electrons through the electron transport chain releases energy and some of this energy is used to generate ATP by the enzyme ATP synthase.

Describe photolysis.

Photolysis uses the rest of the light energy to split water into hydrogen ions and oxygen. The oxygen is evolved (released into the atmosphere) and the hydrogen ions are transferred to the co-enzyme NADP to form NADPH and is then transferred to the Calvin Cycle along with the ATP from earlier.

What is the carbon fixation stage?

The carbon fixation stage is a series of enzyme-controlled reactions which does not require light.

Describe the Calvin cycle.

Carbon dioxide (from the atmosphere) enters the cycle. The enzyme RuBisCO fixes carbon dioxide by attaching it to ribulose bisphosphate (RuBP). producing 3-phosphoglycerate (3PG). The 3PG is then phosphorylated by ATP and combined with hydrogen ions from NADPH to form glyceraldehyde-3-phosphate (G3P). G3P is used to regenerate RuBP and for the synthesis of glucose.

What is the Calvin cycle dependent on?

The Calvin Cycle is the temperature-dependent part of photosynthesis.

What can glucose be used as?

Glucose can be used as a respiratory substrate, synthesised into starch or cellulose or passed to other biosynthetic pathways.

What can biosynthetic pathways lead to?

These biosynthetic pathways can lead to the formation of variety of metabolites such as DNA, protein and fat.