plant structures and their functions

Question 1

what type of reaction is photosynthesis?

Answer 1

endothermic, it is taking in light energy from the environment and transferred to the chloroplasts

Question 2

what is the word equation for photosynthesis?

Answer 2

carbon dioxide + water –> glucose + oxygen

Question 3

what is the chemical symbol for glucose?

Answer 3

C(6)H(12)O(6)

Question 4

how does temperature affect the rate of photosynthesis?

Answer 4

an increase in temperature increases the rate of photosynthesis until the enzyme denatures then the rate decreases

Question 5

how does light intensity affect the rate of photosynthesis?

Answer 5

the higher the light intensity, the faster the rate if reaction

Question 6

how does carbon dioxide concentration affect the rate of reaction?

Answer 6

as the concentration of carbon dioxide increases, the rate of reaction increases

Question 7

rate of photosynthesis practical

Answer 7

• us ruler to place the flask 15cm from the lamp
• leave the flask with pondweed in for 10 mins
• connect the flask to a gas syringe and record the volume of gas produced after 5 mins
• move the lamp 10cm away and repeat the process

Question 8

what is transpiration?

Answer 8

the process that water is lost by from the leaves of plants through the small openings calling stomata

Question 9

what are guard cells?

Answer 9

specialised cells that control the opening and closing of the stomata, they respond to light, temperature and humidity

Question 10

what is translocation?

Answer 10

the movement of substances up or down the phloem

Question 11

what are the 4 adaptations of a leaf?

Answer 11

• stomata: regulate gas exchange in plants
• chlorophyll: it is green so it is really food for absorbing light
• thin: co2 only has short distance to travel to enter the leaf
• large surface area: leaf can absorb more light at once so more photosynthesis

Question 12

what are 3 plant adaptations?

Answer 12

• small leaf shape: reduces amount of water lost through transpiration
• waxy cuticle: prevents evaporation of water
• stomata: pores on the surface of the leaf and can be closed to prevent evaporation of water and opened when co2 is needed for respiration

Question 13

what happens in positive phototropism?

Answer 13

• the plant is exposed to light on one side
• the auxins (growth hormone) moves to the shaded side of the shoot
• auxin stimulates growth there
• this means the shoot bends towards the light
• the plant receives more light so more photosynthesis

Question 14

what happens in negative gravitropism?

Answer 14

• the auxins move to the lower side if the shoot is horizontal
• the cells grow more on the side with lots of auxins so it stimulates growth here
• this makes the shoot bend and grow away from the ground
• this is good because light is most likely away from the ground

Question 15

what are 3 uses for auxins?

Answer 15

• weed killers: too much will cause cells to grow rapidly and die
• rooting powders: cloning plants with desirable features
• promote growth in tissue culture: cloning a plant using tissue culture

Question 16

what are gibberellins?

Answer 16

they allow fruits to grow heavier and larger

Question 17

what are ethenes?

Answer 17

they are used for fruit ripening