Plants and photosynthesis

Question 1

What is the equation for phtosynthesis, word and symbol?

Answer 1

Carbon dioxide + water ….(sunlight and chlorophyll)…. glucose + oxygen

6CO₂ + 6H₂O … [Reaction (light energy)] ..C₆H₁₂O₆ + 6O₂

Question 1

What is a limiting factor?

Answer 1

Something that stops the process happening any faster.

Question 2

What is photosynthesis?

Answer 2

The process that produces food in plants and algae, the food is glucose.

Question 3

Where does photosynthesis happen (mostly)?

Answer 3

In the leaves of all green plants - largely what the leaves are for.

Question 4

What do chloroplasts do and how?

What does it do with its gained energy?

What is the by-product from this?

Answer 4

They contain a green substance called chlorophyll which absorbs sunlight.

It uses this energy to convert CO₂(from the air) and water (from the soil) into glucose.

Oxygen is produced as the by-product.

Question 5

Light as a limiting factor…

What does it do in photosynthesis?

What happens as light levels intensify?

Answer 5

It provides the energy for photosynthesis.

The rate of photosynthesis steadily increases until it levels off when another factor affecting the rate becomes the limiting factor, for example CO₂ levels or temperature.

Question 6

The limiting factors may depend on environmental change… name 3 and why…

Answer 6

Being night - no light for the energy needed for the reaction

Winter - the temperature is too low, too little energy to react

CO₂levels - if everything else is high, then this usually restricts the rate, e.g high density of plants, in rainforests for example

Question 7

How can the ideal conditions for photosynthesis be worked out in an experiment?

Answer 7

Use Canadian pondweed - put into a conical flask in water.

Either count the bubbles produced in 1 minute under different conditions

Or use a gas syringe to collect the oxygen.

Question 8

How do plants use glucose for respiration?

Manafacture

Use

What else is needed for these uses?

Answer 8

The gucose is manafactured in their leaves

Some is used for respiration

This releases energy which enables them to convert the rest of the glucose into other useful substances, to build new cells and for growth

They need to gather minerals from the soil.

Question 9

What affects the rate of photosynthesis?

What are these called when there is little?

Answer 9

Light

CO₂

Temperature

Water

These are the limiting factors of photosynthesis.

Question 10

Name the layer sof plant tissue…

The outer layers, top and bottom…

The central layer…

The tubes…

Answer 10

Epidermal tissue

Mesopyll tissue

Xylem and phloem, xylem carry the water around the plant.

Question 11

How do plants use glucose for cell walls?

Answer 11

It is converted into cellulose for making strong cell walls, especially in a rapidly growing plant

Question 13

Name the three organs that make up plants… What are their components? (simple)….

Answer 13

1. Stems 2. Roots 3. Leaves These organs are made up of tissues.

Question 14

Temperature as the limiting factor…

Why is low temperature the normal limiting factor?

Why is high temperature a limiting factor, at around 45^o, where can this happen?

Answer 14

Low temperatures causes the enzymes needed for photosynthesis to work more slowly.

The enzymes die under these hot conditions of 45^o, therefore slowing the rate. This can happen in very hot places, and in greenhouses if not careful.

Question 15

What is the most common way to artificially create the ideal environment for growing plants?

Answer 15

A greenhouse.

Question 16

How do plants use glucose *(and ions) *for proteins?

Answer 16

Combined with nitrate ions (absorbed from the soil) to make amino acids which are then made into proteins

Question 17

What is the best way to control or alter the limiting factors in an experiment?

CO2

Temperature

Light

How do you make it a fair test?

Answer 17

CO2 - dissolve sodium hydrogencarbonate into the water in different amounts

Temperature - put the plants in a water bath

Light - place a lamp at different distances away from the plant

Keep all of the other variables constant/ the same.

Question 18

How do plants use glucose to store in seeds?

What is it turned into?

Example?

Answer 18

The glucose is turned into lipids (fats and oils), for storing in seeds.

They also store starch.

Sunflower seeds contain a lot of oil, it’s were we get cooking oil and margarine from.

Question 18

How do plants use glucose for startch?

Where?

Why?

Why store it instead of glucose?

Example?

Answer 18

They store it in roots, stems, and leaves

When photosynthesis isn’t happening in the winter the plant needs energy

Starch is insoluble which makes it better for storing, a cell containing lots of glucose would draw up lots of water and swell up

Potatoes and parsnips are swollen stroage organs used for growing a new plant in the spring using the store energy, we eat the strach (carbohydrates)

Question 20

How do greenhouses prevent limiting factors?

Light

Temperature

Answer 20

Artificial light is used by comercial farmers after the sun goes down or during the winter.

They help to trap the sun’s heat, making sure it doesn’t become a limiting factor. In the winter heaters can be used inside these effectively. Also when to hot windows can be opened for ventilation along with fans, and shades.

Question 21

How do greenhouses prevent limiting factors?

CO2

Threats to the plants/ health

Problems with cost?

Answer 21

The CO2 levels can be increased through using a paraffin heater, the by-product of this heater being the CO2.

Enclosed in the greenhouse they are protected from pests, and kept away from diseases. Farmers can easily add minerals and fertilisers to the soil.

Expensive to sort out, but if the levels are reached and balanced just right the plants will be phtotosynthesising at the exact maximum rate for their size, therefore leaving the farmer with the largest profit obtainable.

Question 22

What are the 4 raw materials needed for phtosynthesis and why?

Answer 22

1. Sunlight - provides energy for the process
2. Chlorophyll - contained in chloroplasts - where photosynthesis happens
3. Water - reaches the cells via xylem
4. CO₂ - diffueses into the leaf

Question 23

What are the tissues that make up leaves and what do they do?

Answer 23

1. Mesophyll tissue - where most of the photosynthesis in a plant occurs
2. Xylem and phloem - transport water, mineral ions, and sucrose around the plant
3. Epidermal tissue - this covers the whole plant

Question 24

CO₂ as a limiting factor…

What does it do in photosynthesis?

What happens as CO₂ levels intensify?

How can you increase the levels of CO₂?

Answer 24

It’s one of the raw materials needed in the reaction.

The increase in level makes the rate of photosynthesis steadily increase until it levels off because there is another limiting factor.

Dissolve different amounts of sodium hydrogencarbonate into the water, this is then gives off CO₂

Question 25

Where does photosynthesis happen?

Answer 25

Inside the chloroplasts