Flash Cards for Biology

Here are some extended questions about different topics in Biology.

If your are doing the OCR21st Century Board the new specification, this targets B4 especially.

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Why is glucose stored as starch?
Glucose is stored as starch because starch is insoluble which means the osmotic potential
would stay low. On the other hand glucose is soluble and has a high osmotic potential so
the chemical reaction in the plant cell would be effective.
Explain why less gas is made at 37 degrees Celsius than 22 degrees Celsius
As there was too much heat energy at 37 degrees Celsius this caused the enzyme reaction
to increase and get faster. However, the optimum temperature of the enzyme is 37 degrees
Celsius which means the substrate has the ability to fit in to the enzyme active site. When an
active site has been changed by heating the enzyme the substrate can no longer fit the
active site of enzyme. An active site of enzyme denatures due to high temperatures, as the
bonds between the molecules break down.
Why do plants wilt?
Plats wilt because they have too little water so the water molecules diffuse from inside the
cell (high concentration) to the outside cell (low concentration). The cell membrane shrinks
away from the cell wall.
Why do plants stand up straight when they have enough water?
Plants stand up straight when they have enough water molecules because the structure has
the right shape and size. So the water molecules diffuses from outside (low concentration)
to the inside of the cell (high concentration). The cell membranes bulges and stretches as
they are taking too much water molecule. This will keep the plant straight.
Active Transport
Molecules move against the concentration gradient (from an area of low concentration to
high concentration) using energy from respiration.
Why does bluebells flower in April and May rather than later in summer?
The flowers grow more in April and May than summer because there are limiting factors.
These are factors which prevent the rate of photosynthesis from increasing at a particular
time. In summer the bluebells might not flower because there is a lack of water which
affects the process of photosynthesis whereas in April and May there is more water
available from the rain. Also because Autumn is after summer this means the temperature
will begin to decrease which will affect the rate of photosynthesis.


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