Non-section b questions and answers

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Unit 1, cell biology

Unit 2, molecular biology

Unit 3, genetics

Which genetic condition can be diagnosed by karyotyping? 2013 - Q12
A. Trisomy 21
B. Sickle-cell anemia
C. Hemophilia
D. Colour blindness
Correct answer: Trisonomy 21 (A)

If a father with A-type blood and a mother with B-type blood have a child, what is the probability that the child will have O-type blood? 2013 - Q14
A. 50% chance if both parents have the recessive allele
B. 25% chance if both parents have the recessive allele
C. 0% chance because neither parent has the allele
D. 50% chance if either parent has the recessive allele
Correct answer: 25% chance if both parents have the recessive allele (B)

Unit 4. Ecology

Unit 5. Evolution and biodiversity

Unit 6/11. Physiology part 1 (Nervous, circulatory, endocrine, immune)

Unit 6/11. Physiology part 2 (Respiratory, digestive, locomotive, reproductive, excretory)

Unit 7. Nucleic acids

What are introns? 2013 - Q26
A. Sequences of nucleotides that are removed to form mature RNA in eukaryotes
B. Sequences of nucleotides that are removed to form mature RNA in prokaryotes
C. Sequences that remain in mature RNA after exons have been removed
D. Small pieces of circular DNA that are found in prokaryotes
Correct answer: Sequences of nucleotides that are removed to form mature RNA in eukaryotes (A)

How does meiosis cause Mendel’s law of independent assortment? 2013 - Q34
A. Linked genes are randomly separated
B. The chromosome number is divided twice
C. Crossing-over occurs in Anaphase I
D. Alleles that are not in the same linkage group are segregated
Correct answer: Alleles that are not in the same linkage group are segregated (D)

Why do humans inherit continuous variation with regard to height?
A. The trait for tallness is dominant
B. The height phenotype is polygenic
C. This is a case of multiple alleles
D. Height in humans is polyclonal with multiple alleles
Correct answer: The height phenotype is polygenic (B)

What event occurs only in meiosis? 2016 q18
A. Fusion of gametes to promote genetic variation
B. Random separation of chromatids
C. Random separation of homologous chromosomes
D. Replication of chromosomes
Answer: C

In which situation are alleles exchanged? 2016 q19
A. During the separation of sister chromatids
B. In the transmission of linked genes
C. During fertilization when sperm and egg chromosomes pair up
D. When chiasmata are formed between non-sister chromatids
Answer: D

What is the effect of dominant alleles? 2016 q20
I. They mask the effect of recessive alleles.
II. They become more frequent than recessive alleles in a population.
III. They have a joint effect with recessive alleles when characteristics are co-dominant

A. I only
B. I and II only
C. I and III only
D. I, II and III
Answer: A

The statement is about the genetic control of cat coat colour: 2016 q21
Many genes control cat coat colour. Tabby cats have a coat with stripes. Two of their genes are the tabby gene Mm and the agouti gene Aa.
• The dominant allele M codes for straight stripes, whereas the recessive allele m codes for blotches and whorls instead of stripes.
• The dominant allele A produces two-toned hair, to reveal coat patterns, whereas the recessive allele a causes all coat hair to be black and so hides any pattern.
In a cross between two double heterozygous tabby cats, what would the expected proportion of black offspring be?
A. 1/16
B. 3/16
C. 4/16
D. 9/16
Answer: C

Which are characteristics of a species?
I. The potential to interbreed to produce fertile offspring
II. The formation of a population with members of the same species within a community
III. The overproduction of offspring

A. I and II only
B. I and III only
C. II and III only
D. I, II and III
Answer: A

Unit 8. Metabolism

Metabolic pathways are dependent on enzyme catalyzed reactions. Which terms corresponds with the description. (2018)

A. Allosteric inhibition: the inhibitor binds to the active site of an enzyme.
B. Competitive inhibition: The maximum rate of a reaction is lowered as the substrate concentration increases.
C. Non-competitive inhibition: Raises the maximum rate of reaction of a given enzyme reaction.
D. End-product inhibition: The end product in a metabolic pathway binds to an allosteric site of the first enzyme.

Correct answer: D

What is the source of the oxygen released into the air as a product of photosynthesis? [1] (2018 HL 10)

A. Chlorophyll
B. Carbon dioxide only
C. Water only
D. Both water and carbon dioxide

Answer: C

Which of the following is true of the link reaction of aerobic respiration? [1] (2018 HL 18)

A. The reduction of FAD⁺ occurs.
B. The decarboxylation of pyruvate occurs.
C. It occurs in the cytoplasm.
D. The regeneration of NAD⁺ occurs.
Answer: C. The decarboxylation of pyruvate occurs.

Which technological advance enabled Calvin to perform his lollipop experiment on the light-independent reactions of photosynthesis in 1949? [1] (2017 HL 13)

A. Methods for tracing radioactive carbon incorporated in molecules produced by the alga Chlorella
B. Development of electron microscopes enabling the molecules produced by the alga Scenedesmus to be viewed
C. Methods for changing the wavelength of light shining on the alga Scenedesmus contained in the lollipop
D. Development of X-ray diffraction techniques enabling the molecules produced by the alga Chlorella to be identified
Answer: A. Methods for tracing radioactive carbon incorporated in molecules produced by the alga Chlorella

What is used to reduce NADP in the light-dependent reactions of photosynthesis? [1] (2017 HL 15)
A. Conversion of ATP into ADP + P_i
B. Electrons from Photosystem I
C. Protons from the thylakoid space
D. Oxygen released by photolysis of water
Answer: B. Electrons from Photosystem I

Which gas produces most of the bubbles in bread dough? [1] (2016 HL 11)

A. Oxygen
B. Methane
C. Carbon dioxide
D. Water vapour
Answer: C. Carbon dioxide

Unit 9. Plant biology

Unit 10. Genetics and evolution

Outline the law of independent assortment. [2] (2018 HL 3.a.ii)

The law of independent assortment states that one allele is passed from a parent to an offspring independently of another. It means that the inheritance of one trait does not cause the inheritance of another.

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