Photosynthesis Y9

Question 1

What conversion of energy occurs in photosynthesis?

Answer 1

Light energy –> Chemical Energy

Question 2

What is Autotrophism?

Answer 2

plant capable of synthesizing its own food from simple organic substances

Question 3

Is a plant Autotophic?

Answer 3

Yes

Question 4

What plant organ does this process of photosynthesis occur in?

Answer 4

Leaf

Question 5

What organelle does Photosynthesis take place in?

Answer 5

Chloroplast

Question 6

What pigment does plant require in order to photosynthesise?

Answer 6

Chlorophyll

Question 7

What is the word equation for photosynthesis?

Answer 7

Water + Carbon Dioxide –> Glucose + Oxygen

Question 8

What is the Balanced symbol equation for photosynthesis?

Answer 8

6CO2 + 6H2O → C6H12O6 + 6O2

Question 9

What are the three limiting factors for Photosynthesis?

Answer 9

Temperature, Light Intensity and Co2 concentration.

Question 10

Explain how Light Intensity affects the rate of Photosynthesis?

Answer 10

Light intensity is the limiting factor. As light intensity increases, the rate of p/s increases 2) Rate of p/s levels off. This is because there is another limiting factor – either temp or CO2 concentration.

Question 11

Explain how Co2 concentration affecst the rate of photosynthesis?

Answer 11

CO2 concentration is the limiting factor. As CO2 concentration. increases, the rate of p/s increases 2) Rate of p/s levels off. This is because there is another limiting factor – either temp or light intensity.
1

Question 12

Explain how Temperature affects the rate of Photosynthesis?

Answer 12

Temperature is the limiting factor as the enzymes do not have much kinetic energy. Temp ↑ = K.E ↑= molecules move faster = more E-S complexes formed per second. 2) The rate of p/s will increase until it reaches the optimum temperature. 3) The enzymes denature and E/S complexes can no longer form. Rate of P/S decreases.

Question 13

Essential practical – what does photosynthesis require?

Answer 13

Plants store glucose as starch. We can test for this using iodine. . The positive result is a colour change from orange/brown to blue/black.
1. We must destarch the leaf. We do this by placing the plant in a dark cupboard for 48 hours. This works because starch is broken down into glucose for use in respiration. 2. Now we can see what conditions are needed for photosynthesis to take place No photosynthesis → No glucose → No starch → Negative iodine test. 3. To safely test for starch we must: a. Boil the leaf in water b. Heat the leaf in ethanol (to remove chlorophyll) c. Using a hot water bath d. Test using iodine

Question 14

How is the Light factor removed?

Answer 14

Tin foil placed over leaf

Question 15

How is Carbon Dioxide removed?

Answer 15

Use a variegated leaf

Question 16

Essential practical – the rate of photosynthesis?

Answer 16

Pond weed is useful, because we can measure the volume of oxygen produced. This allows to determine the rate of
photosynthesis.

Question 17

Different independent variables we could investigate & how we would do this?

Answer 17

Light intensity – having a lamp at different distances Colour of light – using different coloured filters
CO2 conc. – add different masses of hydrogen carbonate

Question 18

What are the two ways of measuring Oxygen? (Essential Practical Rate of Photosynthesis?)

Answer 18

1) Counting bubbles produced per minute 2) Gas syringe (more accurate, because bubbles have different sizes)

Question 19

Where are mineral ions absorbed?

Answer 19

Roots

Question 20

How are mineral Ions absorbed?

Answer 20

Active Transport against a concentration gradient.

Question 21

What adaptions does a root have to absorb mineral ions?

Answer 21

Large SA:V

Question 22

What is the use of Nitrates in plants?

Answer 22

Make amino acids and then proteins for growth

Question 23

What is the use of Magnesium in Plants?

Answer 23

Making chlorophyll, to absorb light in photosynthesis

Question 24

What is the use of Potassium in plants?

Answer 24

Helps enzymes needed for photosynthesis and respiration

Question 25

What is the use of Phosphate in plants?

Answer 25

Used in DNA and cell membranes

Question 26

What is a mineral ion?

Answer 26

An ion is a mineral or element that has a positive or negative charge.

Question 27

What happens when there is a deficiency in Nitrates?

Answer 27

Stunted Growth/Yellow older leaves

Question 28

What happens when there is a deficiency in Magnesium?

Answer 28

Yellow leaves

Question 29

What happens when there is a deficiency in Potassium?

Answer 29

Poor flower/Fruit Growth/Discoloured Leaves

Question 30

What happens when there is a deficiency in Phosphates?

Answer 30

Poor root growth/Purple Leaves

Question 31

Is a leaf an organ, organelle, cell or tissue?

Answer 31

Organ

Question 32

What is a leaf specialised for?

Answer 32

To increase the rate of photosynthesis

Question 33

How is a leaf specialised for obtaining light?

Answer 33

Broad Shape gives a large SA
Palisade cells are packed full of chloroplasts These contain chlorophyll which allows them to absorb light The upper epidermis is transparent allowing light through

Question 34

How is a leaf specialised for Obtaining Carbon Dioxide?

Answer 34

Broad shape gives large SA
Holes called Stomata allow Co2 to diffuse in
Leaf is thin- reducing the diffusion distance
Mesophyll layer contains many air spaces

Question 35

How is a leaf specialised for obtaining water?

Answer 35

Water comes from the roots in the xylem vessels.

The waxy cuticle prevents water loss Guard cells can close the stomata