Chapter 6

Question 1

What is photosynthesis?

Answer 1

The process by which plants synthesise carbohydrates from raw materials using energy from light

Photosynthesis is vital for life on Earth.

Question 2

State the word equation for photosynthesis.

Answer 2

carbon dioxide + water → glucose + oxygen in the presence of light and chlorophyll

This equation summarizes the inputs and outputs of the photosynthesis process.

Question 3

What is chlorophyll?

Answer 3

A green pigment found in chloroplasts

Chlorophyll captures light energy for photosynthesis.

Question 4

What is the balanced chemical equation for photosynthesis?

Answer 4

6CO2 + 6H2O → C6H12O6 + 6O2

This equation represents the chemical transformation during photosynthesis.

Question 5

List the ingredients needed for photosynthesis.

Answer 5

• Sunlight
• Carbon Dioxide
• Water

These ingredients are essential for the photosynthesis reaction.

Question 6

Where does photosynthesis take place in plants?

Answer 6

In chloroplasts found in plant leaves

Chloroplasts contain chlorophyll and other molecules essential for photosynthesis.

Question 7

What does the photosynthesis reaction convert?

Answer 7

Carbon dioxide and water into glucose and oxygen

This conversion is crucial for plant energy and oxygen production.

Question 8

What is produced during photosynthesis that provides energy for the plant?

Answer 8

Glucose

Glucose can be used in respiration or stored as starch.

Question 9

What are the other uses of glucose in plants?

Answer 9

• Starch for energy storage
• Cellulose for cell walls
• Sucrose for transport in the phloem
• Nectar to attract insects for pollination

Glucose serves multiple functions beyond energy.

Question 10

What adaptations do most leaves have for photosynthesis?

Answer 10

Large surface area and thin structure

These features maximize light absorption and gas exchange.

Question 11

Identify the structures in a leaf of a dicotyledonous plant.

Answer 11

• Chloroplasts
• Cuticle
• Guard cells
• Stomata
• Upper epidermis
• Lower epidermis
• Palisade mesophyll
• Spongy mesophyll
• Air spaces
• Vascular bundles
• Xylem
• Phloem

Each structure plays a role in photosynthesis and plant function.

Question 12

What is the function of upper epidermic cells in a leaf?

Answer 12

Secrete a waxy substance forming the cuticle to reduce water loss

Epidermic cells do not contain chloroplasts and cannot photosynthesize.

Question 13

What is the role of palisade mesophyll cells?

Answer 13

Main function is photosynthesis, containing large numbers of chloroplasts

These cells are located close to the top of the leaf for maximum sunlight access.

Question 14

What do stomata do?

Answer 14

Allow diffusion of carbon dioxide and oxygen in and out of the leaf

Stomata are surrounded by guard cells that regulate their opening and closing.

Question 15

What are the limiting factors of photosynthesis?

Answer 15

• Supply of raw materials (CO2 and water)
• Amount of sunlight
• Temperature

These factors affect the rate of photosynthesis.

Question 16

What nutrients do plants need from the soil?

Answer 16

• Nitrate ions for amino acids
• Magnesium ions for chlorophyll

These nutrients are essential for plant growth and function.

Question 17

True or false: Plants can live off just photosynthesis.

Answer 17

FALSE

Plants require additional nutrients from the soil for proper functioning.

Question 18

What happens to the rate of photosynthesis when light intensity is increased?

Answer 18

As light intensity increases, the rate of photosynthesis also increases because more light energy is available for the light-dependent reactions. However, the rate eventually plateaus when light is no longer the limiting factor

This is observed in graphical representations of photosynthesis rates.

Question 19

What is the effect of varying carbon dioxide concentration on photosynthesis?

Answer 19

The rate of photosynthesis increases as carbon dioxide concentration increases, until it reaches a point where it plateaus because carbon dioxide is no longer the limiting factor

This relationship is crucial for understanding photosynthesis efficiency.