Biochemical Processes in Cells

Question 1

ATP & ADP

Answer 1

Energy in eukaryotic cells is transported within cells by small and mobile ATP molecules. ATP stores energy in a high-energy bond that attaches the third phosphate group to the ADP molecule.

When energy is required, the high-energy bond is broken, releasing energy, a phosphate group and ADP.

Question 2

Photosynthesis Chemical Equation

Answer 2

Sunlight
Carbon dioxide + Water → Glucose + Oxygen
Chlorophyll

Question 3

Photosynthesis - Plant Cells

Answer 3

The process where plants use light energy, trapped by chlorophyll, to break down water and carbon dioxide molecules, and build them up into oxygen, glucose and water molecules.

Question 4

Photosynthesis Stages

Answer 4

Each stage is not a single chemical reaction, but consists of a series or chain of reactions:

Light phase - in the grana of the chloroplast, chlorophyll absorbs light energy and uses it to split water into hydrogen and oxygen (photolysis)

Light-independent phase (sometimes referred to as the carbon fixation stage) - in the stroma of the chloroplast, a cycle of reactions builds glucose (sugar) from carbon dioxide and hydrogen from water.

Question 5

Cellular Respiration - Plants & Animal Cells

Answer 5

When glucose and oxygen combine in the process of aerobic cellular respiration, energy is produced along with water and carbon dioxide.

Question 6

Cellular Respiration Chemical Equation

Answer 6

Glucose + Oxygen → Carbon dioxide + Water + energy (ATP)

Question 7

Cellular Respiration Stages

Answer 7

1. Occurs in the cytoplasm and is called glycolysis.
   One glucose molecule is broken down into two pyruvate molecules
   and two ATP.
2. Occurs in the mitochondria where pyruvate, in the presence of
   oxygen (aerobic cellular respiration), is broken down to release
   carbon dioxide, water and 34 ATP.

Question 8

Anaerobic Cellular Respiration

Answer 8

WITHOUT OXYGEN

Cellular respiration produces ethanol and carbon dioxide in bacteria, yeast and plant cells (fermentation), and lactic acid in animal cells.

Two ATP molecules are produced in this process for the respiration of each molecule of glucose.

Question 9

Anaerobic Cellular Respiration Chemical Equation

Answer 9

Glucose → Ethanol + Carbon dioxide + energy (ATP)
OR
Glucose → Lactic acid + energy (ATP)

Question 10

Wastes

Answer 10

Waste products not required in cellular reactions can be removed by simple diffusion (oxygen and carbon dioxide) or osmosis (water and waste chemicals that dissolve in water) through the cell membrane.

When parts of the cell break down, wear out or die, they also need to be removed. Lysosomes, which contain digestive enzymes, are responsible for breaking down these ‘old’ cell parts and other cellular waste.

Any of these wastes that can’t be eliminated in this way by the lysosome are packaged into vesicles and removed by exocytosis.