IB Biology SL Theme A: Unity and diversity questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Question 1

Multiple choiceEasy1 mark

A student is examining a reaction mixture used to build an RNA strand. Which description identifies the monomers and reaction involved?

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Answer: B. RNA is a polymer formed when nucleotide monomers are joined by condensation.

A: substitutes hydrolysis, which breaks polymers rather than joining monomers.
C: substitutes amino acids, which are monomers used to form polypeptides.
D: substitutes DNA for the RNA polymer specified.

Remember: condensation builds polymers from monomers; hydrolysis breaks them down.

Question 2

Multiple choiceEasy1 mark

During a practical, students compare a skeletal muscle fibre with a mature phloem sieve tube element. Which nuclear arrangement should they record?

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Answer: D. Skeletal muscle fibres have many nuclei, whereas mature phloem sieve tube elements lack a nucleus.

A: assumes both cell types have the usual single nucleus.
B: assumes a mature sieve tube element retains one nucleus.
C: treats the skeletal muscle fibre as having only one nucleus.
Remember: skeletal muscle fibres are multinucleate, while mature sieve tube elements are anucleate.

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