Topic1.2 - Photosynthesis & Plants

Question 1

Photosynthesis equation

Answer 1

carbon dioxide + water ———–> oxygen + glucose

light + chlorophyll, above +below arrow

Question 2

Testing leaves for starch

Answer 2

(1) Destarching the leaves
(2) Boiling in water
(3) Boiling in ethanol
(4) Dipped in water
(5) Iodine added

Question 3

During testing leaves for starch why are the leaves destarched

Answer 3

Ensures that any starch detected was formed under experimental conditions - this involves placing them in the dark for 48 hours

During this time the plant uses up stored starch in the leaves for respiration

Question 4

During testing leaves for starch why are the leaves boiled in water

Answer 4

Kills the leaf by stopping all chemical reactions

Question 5

During testing leaves for starch why are the leaves boiled in ethanol

Answer 5

Removes green pigment (chlorophyll), so any colour change can be seen clearly

Question 6

During testing leaves for starch why are the leaves dipped in water

Answer 6

Softens the brittle leaf (from the alcohol)

Question 7

During testing leaves for starch why is iodine added

Answer 7

If starch is present iodine will change from yellow/brown to blue/black

Question 8

Why are variegated leaves used?

Answer 8

They’re used to show the importance of chlorophyll in photosynthesis

Question 9

Why is a heat shield put in front of the elodea (pondweed)?

Answer 9

• to stop temperature from affecting the rate

- to stop temperature from killing the plant

Question 10

Test for oxygen

Answer 10

Relights a glowing splint

Question 11

Uses for the products of photosynthesis

Answer 11

Growth
Storage
Respiration

Question 12

The products of photosynthesis are used by a plant for …

The glucose produced can be…

Answer 12

Respiration

Can be converted into cellulose for cell walls, amino acids for growth, lipids for energy and starch for the storage of energy.

Question 13

The balance between photosynthesis and respiration

Answer 13

The products of photosynthesis (oxygen and glucose) are used in respiration.

The products of respiration (water and CO2) are used in photosynthesis.

Question 14

What is used to detect changes in CO2 concentration?

Answer 14

Bicarbonate indicator

Question 15

Colour of bicarbonate indicator in normal CO2 levels (0.04%)

Answer 15

Red/orange

Question 16

Colour of bicarbonate indicator when CO2 concentration is decreased

Answer 16

Purple

Question 17

Colour of bicarbonate indicator when CO2 concentration is increased

Answer 17

Yellow

Question 18

When do plants respire?

Answer 18

All the time

Question 19

When do plants photosynthesise?

Answer 19

When light is available

Question 20

At certain times of the day the rate of photosynthesis and respiration within a plant balance out. This is called the…

Answer 20

Compensation point

Question 21

Chemical equation for photosynthesis

Answer 21

chlorophyll
6CO2 + 6H2O ———->
light

C6H12O6 + 6O2

Question 22

Factors affecting the rate of photosynthesis

Answer 22

CO2 concentration (using sodium hydrogen carbonate)

Light intensity

Temperature

Question 23

Factors affecting rate: CO2 concentration

Answer 23

CO2 is a reactant - if it’s in short supply, the rate of photosynthesis would drop

Question 24

Factors affecting rate: light intensity

Answer 24

The more light energy absorbed, the faster the rate of photosynthesis

Question 25

Factors affecting rate: temperature

Answer 25

In low temperatures, the molecules aren’t moving as quickly so are less likely to collide and the rate of photosynthesis would decrease

Question 26

How to find the rate of photosynthesis with Elodea?

Answer 26

Counting the number of bubbles of oxygen given off per minute, when sodium hydrogen carbonate is added

Question 27

If one or more factors are in short supply the rate of photosynthesis is limited.

The factor that limits the rate is known as the …

Answer 27

Limiting factor

Question 28

Adaptations of the leaf : palisade mesophyll layer with chloroplasts

Answer 28

Tall thin cells packed with chloroplasts - ideal for trapping light

Question 29

Adaptations of the leaf : stomata

Answer 29

Tiny pores in the leaf that allow gases to enter and leave the leaf. More on the lower surface than on the upper surface

Question 30

Adaptations of the leaf : guard cells

Answer 30

Sausage shaped cells that surround the stoma. Control the size of stomata in order to reduce water loss

Question 31

Adaptations of the leaf : cuticle

Answer 31

Waxy transparent layer that reduces evaporation but allows light through

Question 32

Adaptations of the leaf : upper epidermis

Answer 32

A layer of thin cells that act as a protective layer

Question 33

Adaptations of the leaf : spongy mesophyll with many air spaces

Answer 33

Loosely packed cells with large air spaces between. Site of gas exchange - air spaces make diffusion of gases more efficient

Question 34

Adaptations of the leaf : phloem

Answer 34

Thin walled tubes transporting sugars in solution

Question 35

Adaptations of the leaf : xylem

Answer 35

Thick walled tubes transporting water and minerals

Question 36

Adaptations of the leaf : vein

Answer 36

Provides support and transport systems for the leaf

Question 37

How are leaves adapted to absorb maximum light?

Answer 37

By being thin, having a large surface area, a transparent waxy cuticle and many chloroplasts in the palisade layer

Question 38

Any plant that is grown for profit is known as a …

Answer 38

Crop

Question 39

Why is it important that crops are grown in the best possible conditions?

Answer 39

To ensure you get the maximum yield and therefore profit

Question 40

Why are plants grown in greenhouses?

Answer 40

Makes it easier to control the various factors

Question 41

Temperature and CO2 levels can be optimised through the use of…

Answer 41

Paraffin heaters
Artificial lights
Automatic sprinkler systems

Question 42

How do plants receive the correct minerals?

Answer 42

Fertilisers are applied

Question 43

How does the cost of this equipment affect the sale of the crop produced?

Answer 43

The cost of installing such equipment must be balanced against any extra profit from the added crop produced