8.2 Respiration

Respiration is a life process carried out by all organisms to release energy for cellular processes.

State two uses, in an animal cell, of the energy released during respiration.

The diagram shows an animal cell.

Identify the letter, from W-Z, that indicates the sub-cellular structure where respiration takes place.

(1)

Name the sub-cellular structure identified in part (i),

Complete the following sentence about respiration. Use each word once, more than once or not at all.

Respiration releases energy from ............... . There are two types of respiration that occur in animal cells: ............... respiration occurs in the absence of ............... and produces a ............... amount of energy. ............... respiration occurs when ............... is present and produces a ............... amount of energy.

Complete the table with a (✓) or a (X) to show the products and reactants of aerobic respiration in animals.

Earthworms are decomposers which break down dead plant and animal material in the soil. Decomposition is faster in aerated soil because the earthworms can respire aerobically.

Explain why aeration of the soil ensures that the earthworms can respire aerobically?

If the ground becomes waterlogged then less oxygen will be available in the soil and the earthworm will need to respire anaerobically.

Give the word equation used to represent anaerobic respiration in earthworms.

An oxygen debt is often associated with anaerobic respiration. 

Describe the process that occurs in the human body during an oxygen debt.

The table below lists some other features of aerobic or anaerobic respiration.

Complete the table to indicate whether the statements apply to aerobic respiration, anaerobic respiration or both.

The first statement has been completed for you.

Respiration is a vital process that provides cells with the energy they need to carry out various functions. This process can occur through aerobic respiration, which requires oxygen, or anaerobic respiration, which occurs in the absence of oxygen. 

In an environment with fluctuating oxygen levels, cells need to adapt to varying conditions. 

Which metabolic strategy would be the most adaptive for these cells?

There are several differences and similarities between aerobic respiration and anaerobic respiration in plants.

Complete the Table 1 below.

Table 1

Suggest an environment in which anaerobic respiration might be necessary for plants and fungi.      

An unbalanced chemical equation for anaerobic respiration in plants is shown below.

C₆H₁₂O₆ → C₂H₅OH + CO₂                                                                               

Write the balanced chemical equation.

Respiration is an exothermic reaction.

Justify this statement.

A student carries out an experiment to demonstrate that respiration is an exothermic reaction. The apparatus is shown in Figure 1.

Figure 1

State the variable that the student will be measuring in the experiment and describe how they will measure it.

Explain why the student has included flask A in their experiment.

Suggest how the student could ensure that their results were reliable.