IB Biology HL A2.2.7 Processes of Life in Unicellular Organisms Questions

Practise IB Biology HL A2.2.7 by identifying nutrition, metabolism, response, homeostasis, growth and reproduction as functions of unicellular life.

Exam points

Identify nutrition, metabolism, response, homeostasis, growth and reproduction as functions carried out by unicellular organisms.
Explain how one unicellular cell performs life functions without specialized tissues, using a named organism or structure.
Compare a named unicellular organism with humans for a life function such as excretion or response.
Identify binary fission as reproduction in a unicellular prokaryote.

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Study A2.2.7—Processes of life in unicellular organisms conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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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.

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IB Biology HL A2.2.7 Processes of Life in Unicellular Organisms Questions question 1