Photosynthesis - 8B.1a

Question 1

Where does photosynthesis happen?

Answer 1

Leaves.

Question 2

Photosynthesis is the opposite of…

Answer 2

Respiration

Question 3

How does the air get in and out of the leaves? (2)

Answer 3

Through STOMA (pores in the bottom of leaves)

Question 4

How does water get around the leaves?

Answer 4

Through VEINS in the leaves.

Question 5

What gets into the leaves through the stoma?

Answer 5

OXYGEN in the air

Question 6

What leaves the leaves through the stoma?

Answer 6

CARBON DIOXIDE in the air

Question 7

Where does the CO2 come from?

Answer 7

It’s the product of RESPIRATION that takes place all the time in the plant.

Question 8

Write out the basic chemical equation for photosynthesis.

Answer 8

CO2 + H2O (in presence of sunlight and chlorophyll) = Sugar + O2

Question 9

Name the organelle in the cell where Photosynthesis takes place

Answer 9

Chloroplasts

Question 10

What chemical is in the Chloroplasts?

Answer 10

Chlorophyll

Question 11

What is the sugar stored as?

Answer 11

Starch

Question 12

List steps of experiment to prove a leaf needs LIGHT in order to make starch? (4)

Answer 12

1. DESTARCH 2 plants (leave in dark for 2-3 days)
2. Keep Plant 1 (TEST PLANT) in dark (no LIGHT) for 1-2 days
3. Put Plant 2 (CONTROL) in LIGHT for 1-2 days
4. carry out a STARCH test and compare the test plant to the control plant.

Question 13

How do you do a STARCH TEST? (8 marks - the 4 steps, and what each is for).

Answer 13

1. BOILING WATER for 1-2 minutes. KILLS the leaf and removes the WAXY layer.
2. BOILING in ETHANOL for 2-3 mins - breaks down the membrane and removes the green chlorophyll.
3. WASH in HOT WATER for 1-2 minutes (SOFTENS)
4. ADD IODINE (if starch present, the Iodine will turn dark brown)

Question 14

What experiment do you do to prove a plant makes oxygen? (5)

Answer 14

1. Put some POND WEED under water, but with plenty of LIGHT
2. Collect the BUBBLES
3. TEST for oxygen (RELIGHTS a glowing splint).

Question 15

What experiment would you do to show that plant TRANSPIRE (water flows through them)?

Answer 15

1. Attach a shoot (with leaves) to a glass tube with water and an air bubble.
2. Measure how far the bubble goes in a certain time.
   [note: I think this is a bit unclear. suggest you double-check in textbook]

Question 16

List 5 steps of experiment to prove a leaf needs Carbon Dioxide in order to make starch? (4)

Answer 16

1. DESTARCH 2 plants (leave in dark for 2-3 days)
2. Keep Plant 1 (TEST PLANT) in seales container with no CO2 (container contains SODA LIME) for 1-2 days
3. Put Plant 2 (CONTROL) in normal air with CO2 for 1-2 days
4. carry out a STARCH test and compare the test plant to the control plant.

Question 17

When doing CO2 and LIGHT experiments, what would you need to do to make the tests are FAIR?

Answer 17

Make sure that only one of the conditions is being changed between the two test plants. So, for example, you need to make sure that TEMPERATURE, availability of WATER, LIGHT and AIR are equal (other than those specific factors being tested). Particularly tricky in the LIGHT experiment, for example, because the light bulb may affect temperature.
Also make sure that the plants are similar size and condition before the experiment.