Photosynthesis

Question 1

What is photosynthesis

Answer 1

The process in which light is trapped by chlorophyll and used to convert carbon dioxide and water into glucose and oxygen

Question 2

What 4 conditions are essential for photosynthesis

Answer 2

Light
Chlorophyll
Carbon dioxide
Water

Question 3

What are factors which limit photosynthesis rate

Answer 3

Light Intensity - the brighter the light faster photosynthesis

Plentiful Supply of water - plentiful water = increased photosynthesis rate

CO2 concentration - increased CO2 = increased photosynthesis

Colour of light - chlorophyll absorbs red orange blue indigo and violet light most effectively so photosynthesis occurs faster in these colours

The temperature - as temperature rises rate if photosynthesis increased above 35 degrees it decreases as enzymes are denatured

Question 4

Why do plants need minerals

Answer 4

For healthy growth they are absorbed through the food dissolved in soil water

Question 5

Nitrate

Answer 5

For making amino acids which are used to make protein without it plant will suffer from stunted growth

Question 6

Magnesium

Answer 6

For making chlorophyll without this plants leaves will turn yellow

Question 7

How are leaves adapted for photosynthesis

Answer 7

Large surface area to absorb light rays
A thin shape si gases can diffuse In and out easily

Chloroplasts which contain chlorophyll to absorb light energy

Veins to support the leaf and carry substances to and from all of the leafs cells

Question 8

Testing a leaf for starch

Answer 8

Drop leaf in boiling water to remove waxy cuticle and soften the leaf

Out the leaf into ethanol in a boiling tube and heat this to extract green chlorophyll so you can see the results
Wash the white leaf in hot water then add a few drops of iodine solution
If photosynthesis has occurred leaf will turn black because starch is present

Question 9

What color does iodine turn in presence of starch

Answer 9

From brown to blue black

Question 10

Where is starch made in plants

Answer 10

Only where it’s green - places that contain chlorophyll

Question 11

What does placing a plant with soda lime in a bell jar do

Answer 11

Deprives it of carbon dioxide so it’s unable to make starch

Question 12

How does the plant make starch

Answer 12

Produces glucose from photosynthesis , its then joined in chains to make starch molecules ( a polysaccharide )

Question 13

What does chlorophyll do

Answer 13

Absorbs the light energy needed for ohtosyntheis

Question 14

How does the cuticle help te leaf

Answer 14

Reduces water loss by evaporation and acts as a barrier to enterance of disease microorganisms

Upper and lower epidermis have few chloroplasts and are covered by the cuticle

Question 15

How do stomata help leaf

Answer 15

In lower epidermis m
Allows carbon dioxide to diffuse into leaf to reach the photosynthetic tissues . Allow oxygen and water vapour to diffuse in . Each stomata is formed as a gap between two guard cells . In sunlight they become Turgud this opens the stomata which increases gas exchange . Low light causes them to become flaccid this closes the stomata and decreases water loss

Question 16

What is the mesophyll

Answer 16

Two layers of photosynthetic cells in the middle of the leaf mist photosynthesis takes place here

Made up of the Palisade layer- densely packed for lost of photosynthesis contain many chloroplasts and close to light source as the upper epidermis is transparent

Below the pallaside layer is the spongy layer
Loosely packed cells with air spaces between them they photosynthesise but have less chloroplasts than the palisade layer .gas exchange occurs here and air spaces allow oxygen and water vapour to exit the mesophyll and carbon dioxide to come in

Question 17

Why Is starch more useful than glucose

Answer 17

Storage substance insoluble so can be stored in leads and roots also takes up less space than glucose

Question 18

What’s the vein

Answer 18

Contains xylem to bring water and salts and phloem to transport sucrose to other respiring parts of the plants that cannot photosynthesis

Question 19

How is leaf adapted for gas exchange

Answer 19

Stomata allow CO2 in and oxygen out
Air spaces in the spongy layer allow circulation of air
Guard cells determined when photosynthesis can occur and

Question 20

How do plants use glucose

Answer 20

Some is used for respiration
Some is turned into starch for storage by polymerisation
Some is turned into sucrose for transport
Some is turned into cellulose for plant walls
By polymerisation
Sugar can be converted into lipids which are stored in seeds
Sugars can be combined with nitrates to make proteins and DNa
Sugars can be combined with magnesium to make chlorophyll

Question 21

Phosphate

Answer 21

Making DNA deficiency leads to poor root growth younger leaves go purple

Question 22

Potassium

Answer 22

Needed for enzymes of respiration and photosynthesis to work
Deficiency is yellow leaves with dead spots