Topic 4 - Bioenergetics

Question 1

What is the equation for photosynthesis?

Answer 1

Carbon dioxide + water -> glucose and oxygen

Question 2

Where in a plant does photosynthesis take place ?

Answer 2

In the chloroplasts in green plant cells , they contain chlorophyll that absorbs light.

Question 3

Is photosynthesis exothermic or endothermic?

Answer 3

Endothermic

Question 4

What are the five main ways that plants use glucose?

Answer 4

For respiration.
Make cellulose- for cell walls
make amino acids - glucose is combined with nitrate ions to make amino acids
store as fats or oils - turned into lipids for storing in seeds
stored as starch - stored in the roots for when there is lack of photosyntheis, starch is insoluble

Question 5

What are the limiting factors for photosynthesis?

Answer 5

Light intensity
Co2 concentration
temperature
amount of chlorophyll

Question 6

Describe the graph for the effect of light intensity on the rate of photosynthesis.

Answer 6

As the light intensity increases, so does the rate of photosynthesis but only up to a certain point.
Beyond a certain point the rate of photosynthesis will stop increasing even if light intensity increases.
This is because another factor such as co2 or temperature has become the limiting factor.

Question 7

Describe the graph for the effect of carbon dioxide on the rate of photosynthesis.

Answer 7

The amount of c02 only increases the rate of photosynthesis up to a point, After this the graphs flattens out.
This is because there is now another limiting factor for example temperature , and light intensity.

Question 8

Describe the effect of temperature on the rate of photosynthesis.

Answer 8

When the temperature is too low, it becomes a limiting factor as the enzymes work slowly in cold temperatures.
As the temperature increases, the rate of photossynthesis increases.
However, if it is too hot, enzymes will be damaged and photosythesis will decrease.

Question 9

Describe a method to investigate the effect of light intensity on pondweed ( required practical ).

Answer 9

1) take a boiling tube and place it 10cm away from an led light.
2)fill the boiling tube with sodium hydrogen carbonate solution.
3) Put a piece of pondweed into the boiling tube with the cut end at the top.
4) leave for 5 mins to acclimatise to the conditions.
5) bubble of oxygen should be produced from photosynthesis
6) start a stopwatch and count the number of bubbles produced in one minute,
7) repeat a calculate mean number of bubbles.
8) Repeat the experiment placing the test tube at different distances to the light source.

Question 10

WHat is the inverse square law?

Answer 10

light intensity decreases in proportion to the square of the distance.
If you halve the distance , the light intensity will be four times greater .

light intensity ‘is proportional to ‘ 1/distance ^2

Question 11

Use the inverse square law to calculate the light intensity when the lamp is 10cm from the pondweed.

Answer 11

1/d^2

1/10^2

= 0.01

Question 12

What are ways that farmers can artificially create ideal conditions for plants?

Answer 12

Geenhouses- trap suns heat and make sure temperature is not a limiting factor.
Artificial light - when there is no sun
Paraffin heater- as the paraffin burns it releases carbon dioxide , increasing the ocncentration for photosynthesis.
fertilisers- provides minderals for the plants

Question 13

What is respiration?

Answer 13

Respiration is the process of transferring energy from glucose which goes on in every cell.

Question 14

Is respiration exothermic or endothermic?

Answer 14

Exothermic, it transfers energy to the environment.

Question 15

Give three examples of how organisms use the energy transferred from respiration.

Answer 15

To build up larger molecules from smaller ones (proteins from amino acids)
USed to allow muscles to contract.
To keep body temperature steady in colder surroundings.

Question 16

What is metabolism ?

Answer 16

The sum of all of the reactions that happen in a cell or the body.

Question 17

What can lots of small glucose molecules join together to form?

Answer 17

starch
glycogen
cellulose

Question 18

WHat are lipid molecules made of ?

Answer 18

one molecule of glycerol and three fatty acids

Question 19

WHat are amino acids made of ?

Answer 19

glucose and nitrate ions.

Question 20

What are the word and symbol equations for aerobic respiration?

Answer 20

Glucose + oxygen -> carbon dioxide + water

C6 H12 O6 + 602 -> 6C02 + 6H20

Question 21

Where does aerobic respiration take place?

Answer 21

In the mitochondria

Question 22

WHat is anaerobic respiration and when does it happen?

Answer 22

WHen you do exercise and your body cant supply enough ocygen to your muscles, anaerobic respiration takes place.
It is the incomplete breakdown of glucose , making lactic acid.

Question 23

What is the word equation for anaerobic respiration?

Answer 23

glucose -> lactic acid

Question 24

Compare aerobic and anaerobic respiration.

Answer 24

Anaerobic respiration does not transfer nearly as much energy as aerobic respiration.
this is because glucose isnt fully oxidised/ broken down .
Anaerobic respiration is only usefull in emergencies .

Question 25

What is the word equation for anaerobic respiration in plan and yeast cells?

Answer 25

glucose -> ethanol + carbon dioxide

Question 26

What is another word for anaerobic respitration in yeast cells?

Answer 26

fermentation

Question 27

WHat can the products of fermentation be used for >

Answer 27

Bread making- the carbon dioxide makes bread rise
beer and wine making - the fermentation produces alcohol.

Question 28

WHat is the effect of lactic acid on muscles?

Answer 28

causes muscle fatigue / cramps

Question 29

What is oxygen debt?

Answer 29

The amount of oxygen your body nees to react with the build up of lactic acid and remove it from cells.

Question 30

Which organ converts lactic acid to glucose?

Answer 30

The liver