B8 - Photosynthesis

Question 1

Definitions - What does the word ‘endothermic reaction’ mean?

Answer 1

a reaction that requires a transfer of energy from the environment

Question 2

Definitions - What is glucose?

Answer 2

A simple sugar

Question 3

Definitions - What is a ‘limiting factor’?

Answer 3

limit the rate of a reaction. e.g photosynthesis

Question 4

Definitions - What is photosynthesis?

Answer 4

the process by which plants make food using carbon dioxide, water, and light.

Question 5

B8.1 - Describe how plants get the materials needed for growth.

Answer 5

• water: up through the roots - xylem cells
• co2: through stomata on leaves
• light: through top of the leaves
• chlorophyll: in chloroplasts of palisade cells

Question 6

B8.1 - State the word equation for photosynthesis.

Answer 6

Light
CO2 + Water ——–> glucose + oxygen
Chlorophyll

Question 7

B8.1 - Why do plants need light to carry out photosynthesis??

Answer 7

Plants use light to create glucose from water and carbon dioxide.

Question 8

B8.1 - Describe how the leaf is adapted for photosynthesis

Answer 8

Large surface area for maximum light absorption. Thin structure - short distance for CO2 to diffuse into leaf cells

Question 9

B8.1 - Write the balanced symbol equation for photosynthesis.

Answer 9

6CO2 + 6H2O → C6H12O6 + 6O2.

Question 10

B8.1 - Explain how adaptations of the leaf make photosynthesis efficient.

Answer 10

•Large surface area and contain openings called stomata to allow CO2 into the leaf and oxygen out.

Question 11

B8.1 - Explain why chlorophyll is needed for photosynthesis

Answer 11

Chlorophyll absorbs the sunlight used for photosynthesis.

Question 12

B8.2 - What factors affect the rate of photosynthesis?

Answer 12

temperature, carbon dioxide concentration, light intensity

Question 13

B8.2 - Explain why a high temperature affects the rate of photosynthesis

Answer 13

The rate of photosynthesis slows down because the enzymes involved in chemical reactions of photosynthesis are sensitive to temperature and become denatured at higher temp.

Question 14

B8.3 - List some ways in which plants use glucose

Answer 14

make celluose, make starch, respiration, storage, photosynthesis.

Question 15

B8.3 - What are some safety rules for testing for starch?`

Answer 15

Safety goggles

Question 16

B8.3 - describe all the ways plants use glucose, including how they make proteins

Answer 16

Some of the glucose is used for respiration and converted into cellulose for making cell walls. Glucose is combined with nitrates to make amino acids, which are then made into proteins.

Question 17

B8.3 - Explain how and why plants convert glucose to starch for storage

Answer 17

Glucose is converted into starch by a process called polymerization. Glucose is converted into starch as glucose is soluble and starch is insoluble in water so it won’t affect the way water moves in and out of the plant

Question 18

6 Marker Answer - Remember, just bullet point for 6 marks

Answer 18

A - Upper epidermis (protects leaf) they are transparent and let light through.
B - Palisade cells (has lots of chloroplasts) and is where most of the photosynthesis takes place.
C - air space for diffusion of gases and lets oxygen out.
D - guard cells (opens and closes the stomata) - controls the size of the stomata
E - lower epidermis - this lets water vapour in and out of the cell
F - Xylem tubes - transports water and minerals
G - Phloem - transports dissolved sugars

Question 19

What is the inverse square law for photosynthesis?

Answer 19

The rate of photosynthesis is directly proportional to light intensity and inversely proportional (one value increases and one decreases) to the distance from a light source. The inverse square law tells us that the intensity of light is inversely proportional to the square of the distance from the source.

Question 20

What is the inverse square law equation?

Answer 20

New light intensity = original light intensity x original distance from lamp squared over the new distance squared