photosynthesis

Question 1

photosynthesis word equation

Answer 1

carbon dioxide + water (sunlight and chlorophyll) —> glucose + oxygen

Question 2

photosynthesis symbol equation

Answer 2

6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂

Question 3

What absorbs the energy required for photosynthesis?

Answer 3

chlorophyll

Question 4

photosynthesis required practical step by step

Answer 4

-To find out how light affects photosynthesis, place a piece of pondweed in a beaker of water with some sodium hydrogencarbonate to give it carbon dioxide.
-Shine a lamp on the beaker and change how far the lamp is from the plant to change the light intensity, for example 10 cm, 20 cm, 30 cm.
-Use a ruler to measure the distance.
-Keep everything else the same each time, like using the same type and size of pondweed, keeping the temperature steady with a water bath or heat screen, and using the same amount of sodium hydrogencarbonate.
-Let the pondweed adjust for a few minutes at each new distance before measuring.
-Measure photosynthesis by counting the number of bubbles the plant makes in one minute.
-REPEAT! Do each test a few times and take an average to make the results more reliable.

Question 5

Name the green substance which absorbs the light energy.

Answer 5

chlorophyll

Question 6

where in a plant cell can we find chlorophyll

Answer 6

in the chloroplasts

Question 7

In bright sunlight, the concentration of carbon dioxide in the air can limit the rate of photosynthesis. Explain what this means.

Answer 7

In bright sunlight, the plant has enough light to do photosynthesis, but there wouldn’t be enough carbon dioxide. This means the lack of carbon dioxide limits the rate of photosynthesis.

Question 8

what are the 3 rate limiting factors for photosynthesis

Answer 8

light intensity, carbon dioxide concentration, temperature

Question 9

Photosynthesis is a process that takes place in green plants. What type of energy is needed for this process?

Answer 9

light energy

Question 10

Describe two ways you could speed up photosynthesis.

Answer 10

increase carbon dioxide, temperature or light intensity

Question 11

Describe how energy for the photosynthesis reaction is gained by plants.

Answer 11

Plants gain energy for photosynthesis from sunlight. The chlorophyll from chloroplasts absorb the light energy from the sun, this is then used for photosynthesis

Question 12

what is the inverse square law

Answer 12

the intensity of light decreases proportionally to the square of the distance from its source. - it becomes four times weaker if you double the distance.

Question 13

photosynthesis practical:
How could the student measure the rate of photosynthesis more accurately?

Answer 13

-use a funnel with a measuring cylinder
-measure the volume of oxygen gas produced

Question 14

The LED light source does not get hot.
Why is this important?

Answer 14

it helps keep the temperature constant, so the heat doesn’t affect the rate of photosynthesis.

Question 15

how can you increase light intensity, temp and co2

Answer 15

light - south facing gardens, lamp
temp - heaters
co2 - co2 tanks

Question 16

why does the rate of photosynthesis decrease when the temp gets too high

Answer 16

enzymes are denatured at a high temp - they can no longer function properly so the rate decreases

Question 17

what happens to all the glucose made in photosynthesis

Answer 17

-turned into starch (potatoes, carrots…)
-fats and oils (sunflower oil, olive oil…)
-sugars (fruits, honey…)
-cellulose (cell wall)
-protein (beans…)

Question 18

How will the poisonous berries help the deadly nightshade plant to survive?

Answer 18

deters animals, prevents them from eating it

Question 19

Which type of defence mechanism are the berries?

Answer 19

chemical

Question 20

Suggest how the gorse plant is adapted to defend itself.

Answer 20

sharp spines and thorns to prevent herbivores from eating it

Question 21

how to test for glucose

Answer 21

-add benedict solution to a boiling tube, then add the leaf
-heat the mixture in the hot water bath for a few mins
-if glucose is present the solution would change from blue to orange/red

Question 22

how are palisade mesophyll cells and guard cells involved in photosynthesis

Answer 22

palisade mesophyll cells - contain many chloroplasts to absorb light
guard cells - controls the opening and closing of stomata to allow carbon dioxide in and oxygen out

Question 23

HOW TO TEST FOR STARCH

Answer 23

-Place the extracted leaf into a 150cm3 beaker of water and heat until it boils- then turn off the Bunsen
-Put the leaf in a test tube with ethanol and place it in the beaker of hot water - leave for 5 mins
-Pour the ethanol (that turned green) into the sink then place the leaf back into the beaker of water
-Place the leaf on a white tile and add a few drops of iodine solution.
-If starch is present, the iodine will turn blue-black. If there’s no starch, it stays brown-orange.

Question 24

why do plants need nitrate

Answer 24

to make proteins for healthy growth

Question 25

what two main minerals do plants need

Answer 25

nitrate, magnesium

Question 26

why do plants need magnesium

Answer 26

to make chlorophyll needed to absorb light energy for photosynthesis

Question 27

Deficiency of nitrate symptoms

Answer 27

stunted growth

Question 28

Deficiency of magnesium symptoms

Answer 28

yellow leaves

Question 29

Minerals are often taken into plants by ....

Answer 29

active transport

Question 30

what is active transport

Answer 30

the movement of molecules against its concentration gradient, an area of low to high concentration through a membrane

Question 32

Why may plants produce insufficient chlorophyll?

Answer 32

They lack the required nutrients

Question 33

Describe and explain how the rate of photosynthesis varies with temperature

Answer 33

At first the rate of photosynthesis rises with temperature as the particles have more energy and move more quickly. This means they can react more quickly and so the rate is higher. However, as temperature rises above the optimum temperature for the enzymes involved, the enzymes may start to break down. This decreases the rate until it falls to zero (when the enzymes are denatured).

Question 34

The four levels of plant organisation are:

Answer 34

cells ➔ tissues ➔ organs ➔ organ systems

Question 35

A leaf is a

Answer 35

Organ

Question 36

The root, stem, and leaves, together make up an

Answer 36

Organ system

Question 37

palisade mesophyll layer is an example of a

Answer 37

Tissue