B4 Bioenergetics

Question 1

What is photosynthesis?

Answer 1

The process by which plants synthesise glucose using light energy from the sun.
Light energy is converted into chemical energy

Question 2

Where does photosynthesis take place?

Answer 2

Within chloroplasts in leaf palisade cells. They contain chlorophyll, a pigment which absorbs light energy

Question 3

What is the word equation for photosynthesis?

Answer 3

Carbon dioxide + water ——> glucose + oxygen
Light

Question 4

What is the symbol equation for photosynthesis?

Answer 4

6CO2 + 6H2O ———-> C6H12O6 + 6O2
Light

Question 5

Is photosynthesis an endothermic or exothermic reaction and why?

Answer 5

Endothermic
Energy is transferred from the environment to chloroplasts by light

Question 6

How do gases get into and out of a plant?

Answer 6

Leaves have tiny pores called stomata
Stomata allow gases to diffuse into and out of leaves
Carbon dioxide diffuses into the leaf and oxygen diffuses out

Question 7

What is metabolism?

Answer 7

The metabolism of an organism is the sum of all the reactions that take place in a cell or in the body. There are hundreds of thousands of examples of metabolic reactions. A common example is the breakdown of excess proteins in the liver to form urea. Other examples include the reactions of respiration and photosynthesis.

Question 8

What are some common metabolic reactions?

Answer 8

The conversion of glucose to starch, glycogen and cellulose.
The formation of lipid molecules from glycerol and fatty acid molecules.
To use glucose and nitrate ions to from amino acids that are used to make proteins.
The reactions of respiration.
The reactions of photosynthesis.
The breakdown of excess proteins in the liver to form urea for excretion in the urine by the kidneys.

Question 9

What is oxygen debt?

Answer 9

An oxygen debt is the amount of extra oxygen your body needs after exercise to break down the lactic acid that has built up.