B2.2

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What do plants and algae need food for?
To provide the energy for respiration, growth and reproduction
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How do plants make their own food?
Carbon dioxide + water = (+ light energy) glucose + oxygen
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What part of the chloroplasts absorbs the light energy?
The chlorophyll
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What happens to the glucose that is made during photosynthesis?
Some is used immediately and some is converted into insoluble starch and is stored.
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What can you use to test for starch?
Iodine solution
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Why are many leaves broad?
To give them a large surface area for light to fall on
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Why are leaves green?
They contain lots of chlorophyll in their chloroplasts to convert light into energy.
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Why do leaves have lots of air spaces?
To allow carbon dioxide to diffuse into and oxygen to diffuse out of the cells
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What adaptation brings plenty of water to the cells?
Veins
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Where do algae get the carbon dioxide they needs for photosynthesis from?
The water around them
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What do plants need if they are to photosynthesize as fast as they can?
Light, warmth, and carbon dioxide
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What is a limiting factor?
Factor that limits the rate of any reaction (including photosynthesis)
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How does light intensity relate to photosynthesis?
The higher the light intensity the faster the rate of photosynthesis
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How does the rate of photosynthesis change as temperature increases? Why?
Photosynthesis speeds up as temperature increases, because it is controlled by enzymes.
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What happens to the rate of photosynthesis in most plants when the temperature reaches 50 degrees C? Why?
The rate decreases rapidly because the enzymes denature at these temperatures.
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What is the concentration of carbon dioxide in the atmosphere?
0.04 %
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What effect does increasing the concentration of carbon dioxide have on the rate of photosynthesis?
The rate of photosynthesis will increase as the concentration of carbon dioxide increases.
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When are the carbon dioxide levels around the plant highest? Why?
At night, because there is no light for the plant to photosynthesise so it is not taking up the carbon dioxide
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How could we stop carbon dioxide being the rate-limiting factor in photosynthesis?
By growing plants in green houses with increased concentrations of carbon dioxide
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Why do plants and algae need a constant supply of glucose?
As they respire 24 hours a day
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What is the energy from respiration used for?
To build up smaller molecules into larger molecules
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Name two molecules that the plant makes out of glucose.
1. Starch 2. Cellulose
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One of these is a storage molecule, what is the function of the second?
To strengthen the cell walls
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How do plants make amino acids?
They combine sugars with nitrate ions and other minerals from the soil.
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What are these amino acids used to make?
proteins
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What else can plants and algae make using glucose?
Fats and oils
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Why are these often stored in seeds?
As they are a very good source of energy for a new plant as it germinates
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How is food moved around the plant?
In phloem
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Why can’t plant cells store their food as glucose?
Glucose is soluble in water and would affect the water balance of the whole plant if it were stored in cells.
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Why is starch an ideal substance for storage?
It is insoluble in water and so will not affect water balance.
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Where else, other than in cells, is insoluble starch stored?
In tubers or bulbs
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Give an everyday example of one of the previous answers.
Potato or onion
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Why do farmers want their plants to photosynthesise as fast as possible?
It helps their plants grow fast and large so it will help the farmer make a profit.
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What is the major advantage of using greenhouses?
They are warmer than the outside environment so the rate of photosynthesis is faster.
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What effect will greenhouses have on the fruit grown in them?
They will grow faster, fruit earlier and produce higher yields.
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What is most likely to be the limiting factor of photosynthesis early in the morning?
Light levels and temperature
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What is most likely to be the limiting factor on a hot, sunny day?
Carbon dioxide
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What is hydroponics?
Growing plants in water with perfect balance of minerals so nothing slows down
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Where is temperature always a limiting factor?
In cold climates such as the Arctic
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Why are there less herbivores in the Arctic than there are in a temperate climate (like Britain)?
There is only limited plant growth due to the cold.
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How can Venus flytraps survive in soil with little or no nitrates in?
They digest animal protein to produce the nitrates they need.
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How might a plant be adapted to live in areas with low light?
Larger leaves OR more chlorophyll
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What affects the breeding cycles of many animals and plants?
The day length, they only live and breed in regions where the day length and light intensity are right for them
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Why are animals and plants relatively rare in the desert?
There is very little water.
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What happens when it rains in the desert?
A large number of plants grow.
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What do fish require to live in a particular area?
High levels of oxygen dissolved in the water
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What organisms have species that can survive in low oxygen water?
Invertebrates
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Do oxygen levels affect land animals? Why?
Not very much as there is plenty of oxygen in the air and it does not vary very much from place to place
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What is a quadrat?
A square frame that you lay on the ground to outline your sample area
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What are quadrats often used to measure?
Plant and slow-moving animal population size
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How must you choose your sample areas?
At random
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What is quantitative sampling?
It involves taking a number of readings and finding the mean value for those readings.
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What is a transect?
A line, often marked by a tape that you sample at regular intervals
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What does reproducible mean?
It means someone else can do the same investigation and get the same results.
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What does valid mean?
It means the results must answer the question you are setting out to study.
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Why do we need to control variables?
So that only the thing you are testing changes the outcome/results of your study
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Other cards in this set

Card 2

Front

How do plants make their own food?

Back

Carbon dioxide + water = (+ light energy) glucose + oxygen

Card 3

Front

What part of the chloroplasts absorbs the light energy?

Back

Preview of the front of card 3

Card 4

Front

What happens to the glucose that is made during photosynthesis?

Back

Preview of the front of card 4

Card 5

Front

What can you use to test for starch?

Back

Preview of the front of card 5
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