Page 147 - Biology Form Two

Biology for Secondary Schools

of gas exchange between the leaf Aerobic respiration
and the external environment. This is a type of respiration, whereby
oxygen is used to break down glucose
4. Leaves of plants in tropical forests to release energy, carbon dioxide, and
usually have a very large surface water. The following is the chemical
FOR ONLINE READING ONLY
area and are dark green. Explain equation representing the aerobic
how these features help these respiration process:
plants to survive.
Glucose Carbon dioxide
+
5. Briefly explain the mechanism of + Water
gas exchange in plants through Oxygen +
their: (a) leaves Energy
(b) lenticels C H O + 6O → 6CO + 6H O + ATP
6
2
2
2
12
6
(c) breathing roots The energy produced is in the form of
6. Why is gas exchange important in ATP (Adenosine Triphosphate).
plants?
Mechanism of aerobic respiration
Aerobic respiration involves three main
Respiration in mammals
stages, which are glycolysis, Krebs’
Task 6.6 cycle and electron transport chain. In

Search the library and internet sources this chapter, you will learn two stages.
for simulation/animations showing the These are glycolysis and Krebs’ cycle.
mechanisms of aerobic respiration in Glycolysis: Glycolysis is the process by
mammals. which a molecule of glucose is converted

into two molecules of pyruvic acid
Respiration is a process by which food
substances are broken down to release (pyruvate) and ATP. It takes place in the
energy. It is controlled by enzymes. cytoplasm and does not require oxygen.
Enzymes are substances, specifically Glycolysis occurs in both aerobic and
biological molecules that affect the rate anaerobic respiration.
at which a reaction occurs, although
they are not used up in the reaction. During glycolysis, enzymes catalyse
Enzymes are usually protein in nature. the break down of glucose to form two
Respiration takes place in the cytoplasm molecules of pyruvic acid and ATP.
and mitochondria of a cell. There are The pyruvic acid can further be broken
two types of respiration, namely aerobic down in the presence or absence of
respiration and anaerobic respiration. oxygen. If there is oxygen, pyruvic acid

Student’s Book - Form Two 141

05/10/2024 15:36:45
BIOLOGY FORM 2 NEW.indd 141
BIOLOGY FORM 2 NEW.indd 141 05/10/2024 15:36:45