photosynthesis spec questions

Question 1

Define the terms autotropic

Answer 1

living thing that can make its own food from simple chemical substances such as carbon dioxide and light

Question 2

define the term heterotrophic

Answer 2

an organism that eats other plants or animals for energy and nutrients

Question 3

What is the equation for photosynthesis?

Answer 3

carbon dioxide + water —> oxygen + glucose

6CO2 + 6H20 —–> C6H1206 + 602

Question 4

what is the equation for respiration

Answer 4

glucose + oxygen —> carbon dioxide + water

Question 5

Explain energy transfers in photosynthesis

Answer 5

light energy is absorbed by photosynthetic pigements found in chloroplasts. The light energy excites electrons in photosystems which then pass down an electron transport chain. This releases the energy for chemiosmosis which combines ADP and Pi to make ATP

Question 6

explain chemiosmosis

Answer 6

The pumping of protons into the thylakoid membrane setting up a proton gradient, resulting in H+ ions diffusing through the channel of ATP synthase which combines ATP and Pi to make ATP

Question 7

what kind of pigment is chlorophyll a and what is its function

Answer 7

chlorophyll a is a primary pigment , absorbs light energy at colours of blue/red/orange at wavelengths of 450 and 670

Question 8

name the accessory pigments

Answer 8

chlorophyll b, carotenoids xantophyll

Question 9

what is the absorbtion spectra

Answer 9

used to determine the wavelengths absorbed by specific pigments, showing the percentage of light absorbed at each wavelength

Question 10

what is the action spectra

Answer 10

Action spectrum helps to show the relationship between the rate of photosynthesis for a given wavelength

Question 11

what technique can be used to separate pigments

Answer 11

chromotography

Question 12

What are the 2 stages of photosynthesis?

Answer 12

light dependant and light independant
( calvin cycle )

Question 13

Where does the light dependant reaction take place?

Answer 13

thylakoid membrane

Question 14

What 2 things are need for the light dependant reaction

Answer 14

light
water

Question 15

What are the 3 products of the light independent reaction?

Answer 15

glucose
NADP+
ADP + Pi

Question 16

What is photolysis

Answer 16

splitting of a water molecule using light to produce hydrogen ion, oxygen and electrons

Question 17

How is NADP reduced?

Answer 17

Reduced NADP is produced when hydrogen ions combine with the carrier molecule NADP using electrons from the photolysis of water

Question 18

What is photophosphorylation

Answer 18

the process by which light energy is used to produce ATP, the energy currency of cells.

Question 19

What happens in cyclic phosphorylation

Answer 19

only involves PS1 and is where Light energy excites electrons, and energy is used to create an H+ gradient in the same way, with ATP synthase transporting H+ out of the stroma. Less ATP is made via cyclic photophosphorylation, but importantly the electrons aren’t given to NADP the electrons are recycled

Question 20

Where does the light independent reaction take place?

Answer 20

stroma

Question 21

What 2 products of the light dependent reaction are needed for the light independent reaction?

Answer 21

reduced NADP and ATP

Question 22

What are the 3 processes involved in the light independent reaction?

Answer 22

fixation, reduction and regeneration

Question 23

Name the enzyme involved in the Calvin cycle.

Answer 23

RuBisCO

Question 24

What are the products of the Calvin cycle

Answer 24

TP - used to create a hexose sugar

Question 25

What are the limiting factors of photosynthesis?

Answer 25

temperature
CO2 concentration
light intensity

Question 26

How does temperature affect the rate of photosynthesis?

Answer 26

as the light independant stage is controlled by enzymes temperature can increase the rate of photosynthesis however past the optimum temperature enzymes can become denatured and rate of photosynthesis will be very slow

Question 27

How are C4 plants adapted?

Answer 27

​such as maize and sorghum are ​adapted to work at high temperatures​. The enzymes involved in photosynthesis have a ​higher optimum temperature​, so are not damaged by the high temperatures.

Question 28

How are CAM plants adapted?

Answer 28

adapt to arid conditions for photosynthesis by opening their stomata at night to minimise water loss.

Question 29

How can an understanding of the effect of limiting factors on the rate of photosynthesis can be used to increase crop yields?

Answer 29

in order to maximise photosynthesis farmers can ensure that temperature CO2 and light intensity are at their optimum levels. Eg farmers can install CO2 machines, thermastatically control greenhouses, provide lights at night ect.