B2.2 Organisms and the Environment Flashcards Preview

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Flashcards in B2.2 Organisms and the Environment Deck (30)
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What is the equation for photosynthesis?

carbon dioxide + water --(light)--> glucose + oxygen


What is the light energy used for photosynthesis absorbed by?



What is the glucose made from photosynthesis used for?

-It can be used immediately for respiration.
-It can be stored as starch for later use.


What is the test to show that photosynthesis has taken place in a plant?

The iodine test.
-The iodine reacts with starch turning it from yellow to blue.


What are the four main adaptations of leaves?

-Large surface area for light to fall on.
-Contain chlorophyll in the chloroplasts to absorb the light energy.
-They have air spaces allowing gas exchange.
-They have veins which bring water to the cells.


What factors limit the rate of photosynthesis in a plant?

-Intensity of light
-CO2 level.


How does light intensity affect the rate of photosynthesis?

The greater the intensity, the faster the rate of photosynthesis.


How does temperature limit the rate of photosynthesis?

Photosynthesis is controlled by enzymes. The rate of photosynthesis increases with the temperature until the enzymes start to denature.


How does the level of carbon dioxide affect the rate of photosynthesis?

The greater the level of carbon dioxide, the greater the rate of photosynthesis.


What four ways do plants use the glucose they produce?

-Covert into insoluble starch for storage
-Produce fats or oils for storage
-Produce fats, proteins or cellulose for cells and cell walls.


How do plants use glucose to make amino acids?

-Glucose is combined with nitrate and other mineral ions.
-The amino acids are then built up to make proteins.


Why is glucose made into insoluble starch?

If glucose were stored in plant cells it could affect the way water moves in and out of cells affecting the water balance of the plant.
Starch has no affect on the water balance meaning large amounts can be stored.


What is the purpose of making starch?

To provide energy for when it is dark or low light.


What is a tuber or bulb?

They are large storage areas for starch.


Why are greenhouses and poly tunnels used to grow some food?

The temperature inside greenhouses is higher increasing the rate of photosynthesis.


What is hydroponics?

Computer controlled growing conditions for plants with ideal amounts of water and mineral ions in the soil.


Give three advantages of using hydroponics.

-Turnover is fast.
-Crops are clean and unspoilt.
-No ploughing or preparing the land is needed.


Give a disadvantage of using hydroponics.

The systems are expensive to set up.


Give five factors that affect the distribution of living organisms.

-Amount of light
-Availability of water
-Availability of oxygen and carbon dioxide.


Why does temperature affect the distribution of living organisms in cold areas?

Only small plants can survive in cold climates which limits the number of herbivores that can survive in the area.


Why do nutrients affect the distribution of plants?

Most plants struggle to survive in areas with little nutrients. Whereas Venus fly traps thrive since they get nutrients from the flies they digest.


Why does the amount of light affect the distribution of organisms?

Plants are adapted to live in certain light conditions.
The breeding cycles of animals are connected to the day length.


How is the distribution of living organisms in their environment measured?

-Random sampling with quadrats.
-Sampling along a transect.


What is a quadrat?

A square that outlines the sample area.


Why is sample size important?

Sample areas must be random to ensure the validity of the data. ie. the results reflect the distribution of organisms.


What is the difference between using a transect and a quadrat?

A transect is not random.


What is a reproducible investigation?

Other people can carry out the same investigation and get similar results.


What does an investigation have to be, to be valid?

It must answer the question that has been asked..


Why is it important to control variables?

It means other scientists can reproduce the results.


What data can be used as evidence of environmental change?

The investigation must state the problems of collecting data.