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Biology KS3 > Photosynthesis > Flashcards

Photosynthesis Flashcards

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1
Q

How are leaves adapted for photosynthesis

A

They are green bc they contain lots chlorophyll to absorb sunlight

They have a large surface area to maximise the amount of sunlight they can absorb

They are thin ,allowing easy diffusion of gases into and out of the leaf

They have veins (xylem and phloem) to allow the transport of water,mineral ions and glucose(food)

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2
Q

Definition of Controlled Variable

A

Constant and unchanged throughout the course of the investigation

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3
Q

Definition of Independent Variable

A

Something that is changed throughout the experiment

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4
Q

Definition of Dependant Variable

A

Something that is being measured in the experiment

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5
Q

5 Ways Plants can use Glucose

A

Respiration

Making Cellulose

Making amino acids

Stores as oil or fats

Stored as starch

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6
Q

How can you investigate the effect of light intensity

A

By using and aquatic plant like pondweed

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7
Q

Aquatic meaning

A

Lives in water

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8
Q

Explain how to investigate the effect of light intensity with a pond weed

A

Change the distance between the lamp and the pondweed and count the number of bubbles produce per unit Tim e.g. Five per minute

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9
Q

Explain what it means by Respiration

A

Respiration transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances

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10
Q

Explain what it means by ` Making Cellulose`

A

Glucose is converted into cellulose for making strong plant cell walls

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11
Q

Explain what it means by Making amino acids

A

Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins

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12
Q

Explain what it means by ` Stored as oil or fats

A

Glucose is turned into lipids (fats and oils) for storing in seeds

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13
Q

Explain what it means by `Stored as starch and where exactly is it stored

A

Glucose is turned into starch and is stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening, like in the winter. Starch is insoluble which makes it much better for storing than glucose- a cell with lots of glucose in would draw in loads of water and swell up.

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14
Q

“Photosynthesis is endothermic”

What does this mean?

A

Energy is transferred from the environment in the process

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15
Q

What are exothermic reactions?

A

Exothermic reactions are reactions or processes that release energy

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16
Q

Name the 3 factors that can reduce the rate of photosynthesis/ become the limiting factor:

A

intensity of light
Temperature
The concentration of CO2

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17
Q

What does a plant immediately do when it receives glucose?

A

Converts the glucose into starch

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18
Q

Name the 6 steps for the Starch Test:

A

1) Put the plant in the dark for 1 day to get rid of the starch from the leaves
2) Put the plant in the light for 1 day with 1 leaf in a flask with no CO2 and Part of another Leaf covered with black tape BUT NOT THE WHOLE LEAF
3) After that Boil the leaves in water for a few minutes
4) Soak the leaves in warm alcohol to make them go colourless
5) Dip the leaves in water to soften them
6) Dip brown iodine solution onto each leaf

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19
Q

Where do plants get minerals/water from

A

The soil

20
Q

What’s transfers energy from the Sun to a plant

A

Light

21
Q

How can u investigate the effect of light intensity on the rate of photosynthesis

A

U use an aquatic plant e.g. Pondweed.

To do this change the distance between the lamp and the pondweed and count the number of bubbles produced per unit time

22
Q

What is the independent variable in the pondweed test

A

Light intensity ( how close the light is )

23
Q

What is the dependent variable in the pondweed test

A

The number of oxygen bubbles given off

24
Q

What is the Controlled variable in the pondweed test

A

The size of the pondweed
The volume of water used
The waters temperature

25
Q

What is the deficiency symptom if there is not enough nitrates

A

A small plant with yellow older leaves

26
Q

What is the deficiency symptom if there is not enough Phosphates

A

Poor root growth and purple younger leaves

27
Q

What is the Deficiency symptom if there is not enough Potassium

A

Yellow leaves with dead bits

28
Q

The 3 minerals needed for plants

A

Nitrates
Phosphates
Potassium

29
Q

Give an eg of when the Concentration of CO2 is a limiting factor

A

If it’s warm enough and bright enough the amount of CO2 is usually limiting

30
Q

What is the idea of the starch test

A

The idea is to deprive part of either light or CO2 for about a day and test for starch

31
Q

What is the purpose of a thermometer in the Pondweed Test

A

Ensuring temperature stays the same

32
Q

Explain how having lots of chloroplasts near the upper surface is helpful for photosynthesis

A

Means that as much light as possible reaches the chloroplasts

33
Q

Explain how having lots of veins is helpful for Photosynthesis

A

The veins deliver water to the leaf and take away glucose

34
Q

How can the temperature increase and decrease the rate of Photosynthesis

A

As the temperature rises,The rate of photosynthesis increases but Photosynthesis is controlled by Enzymes and most Enzymes denature once the temperature get to 40-50 C . If the Enzymes are denatured, The rate of Photosynthesis will fall

35
Q

Denature meaning

A

Take away or alter the natural qualities of.

36
Q

What is the stomata

A

In the underside of the leaf there are little holes called stomata that allow CO2 to diffuse into the leaf and O2 to diffuse out of the leaf

37
Q

Why does the Spongy layer have loose fitting cells?

A

These let carbon dioxide reach the other cells in the leaf, and also let the oxygen produced in photosynthesis leave the leaf easily

38
Q

Why are leaves important

A

They provide food for the plants and plants provide the food for all living organisms

39
Q

True or False

There is more Carbon dioxide around plants at night because it is not being used up in photosynthesis but driven out by respiration

A

True

40
Q

4 factors that affect photosynthesis

A

Water
CO2 levels
Temperature
Light

41
Q

What are the 5 steps for testing for starch in a leaf

A
  1. Boil a beaker of water and the leaf in the boiling water for 2 min
  2. Remove the leaf from the water and place in a boiling tube containing ethanol
  3. Place the boiling tube in a beaker of hot water and leave until the thank has turned green meaning that the chlorophyll has been removed
  4. Wash the leaf, place on a white tile and add a drop of iodine
  5. If starch is present the iodine turns black
42
Q

Why is nitrates needed

A

Healthy growth

43
Q

Why is phosphates needed

A

Healthy roots

44
Q

Why is potassium needed

A

Healthy leaves and flowers

45
Q

Why is Magnesium needed

A

Production of Chlorophyll

Biology KS3 (5 decks)

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