IB Biology HL 2.2.7 Processes of Life in Unicellular Organisms

Practise IB Biology HL 2.2.7 by comparing unicellular life functions, Paramecium excretion and specialised human organs.

Exam points

Compare excretion in Paramecium and humans using organs, diffusion and waste products.
Relate Paramecium structures to the life functions performed by a unicellular organism.

[Maximum number: 3]

Excretion is one of the functions of life.

Compare and contrast excretion in humans and unicellular organisms such as Paramecium.

Similarities:

a. both expel $\mathrm{CO}_{2}$ /toxins/nitrogenous waste/waste products of metabolism;

Differences:

b. Paramecium does not have special organs for excretion OR

humans do have (special) organs/kidneys/lungs/skin/liver for excretion;

c. unicells/Paramecium excrete through their plasma membrane;

d. (entirely) passive/by diffusion in unicells/Paramecium but humans use energy/active transport (to move blood/air/solutes);

e. humans excrete urea whereas Paramecium excretes ammonia;

Marking guidance:

Reject answers stating
that Paramecium excretes
waste products by exocytosis.

3
max

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A2.2.7—Processes of life in unicellular organisms question 1