Which of the following conclusions did Mendel make from his experiments?

A. Dominant genes are more frequent than recessive genes.
B. Genes are composed of DNA.
C. Traits are inherited in discrete units, one from each parent.
D. Segregation occurs through meiosis.

What causes variation in both sexually and asexually reproducing organisms?

A. Mutations
B. Polygenic inheritance
C. Crossing over
D. Independent assortment

What can lead to reproductive isolation after just one generation?

A. Polyploidy

B. Increased mutation rate

C. Changed allele frequencies

D. Independent assortment of chromosomes

In humans, wavy hair is dominant to straight hair and free ear lobes are dominant to fixed ear lobes. A man and a woman are heterozygous for both characteristics. What is the probability that their  first child will have straight hair and fixed ear lobes?

A. 0
B. 1/16
C. 3/16
D. 9/16

Which of the following processes result in the production of recombinants?

I. Crossing over between linked genes
II. Reassortment of non-linked genes
III. Mutation

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

At which stage of meiosis does a pair of sister chromatids separate?

A. Metaphase I

B. Anaphase I

C. Metaphase II

D. Anaphase II

In a plant, dark leaves are dominant to pale leaves and yellow seeds are dominant to white seeds.

A heterozygous dark-leaved plant with yellow seeds was crossed with a pale-leaved plant with white seeds. A large number of offspring were produced. They were either dark-leaved with yellow seeds or pale-leaved with white seeds in equal number.

What is the most likely cause of this pattern?

A. Crossing over has occurred.

B. The two genes are linked.

C. The traits are polygenic.

D. The genes are codominant.

A test cross of linked genes was performed with fruit flies (Drosophila melanogaster).

What is the most likely explanation for these results not fitting the expected ratio?

A. Crossing-over
B. Non-disjunction
C. Gene mutation
D. Random variation

When do chiasmata form in meiosis?

A. During prophase I
B. During metaphase I
C. During anaphase I
D. During prophase II

Skin colour is a trait controlled by polygenic inheritance. Which statement is correct?
A. Skin colour shows discontinuous variation
B. Individuals show a wide range of phenotypes for skin colour
C. No two people have the same skin colour
D. Children always have the same skin colour as one of their parents

Fossil records show that black bears increased in size during the Ice Age and decreased in size with warmer temperatures. What type of selection do these changes in size represent?

A. Allopatric
B. Directional
C. Disruptive
D. Stabilizing

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.

Which is a statement of Mendel’s law of independent assortment?

A. Allele pairs separate during gamete formation and recombine during fertilization.
B. Allele pairs for different genes separate independently during gamete formation.
C. Unlinked alleles are assorted with a 9 : 3 : 3 : 1 ratio in a dihybrid cross.
D. Allele pairs for the same gene are assorted independently during gamete formation.

Some of the ratios that Morgan investigated in genetic crosses did not correspond with expected Mendelian ratios.  What was the cause?

A. The genetic crosses used insects rather than plants.
B. The results were counted more reliably than Mendel’s.
C. The genes in the genetic crosses were linked.
D. Drosophila has more genes than plants.

How does meiosis cause Mendel’s law of independent assortment?

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.

In which situation are alleles exchanged?

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

The diagram below shows chromosomes during meiosis.

How many chromosomes and chiasmata are visible?

A test cross resulted in these recombinants:

Which of the following was the parental test cross?

Human skin colour shows continuous variation.  What does this indicate about the pattern of inheritance of human skin colour?

A. It is dominant.
B. It is sex-linked.
C. It is recessive.
D. It is polygenic.

Which are the possible recombinants in a dihybrid test cross involving the linked genes JQ/jq?

A. JQ/jq and JJ/Qq

B. Jq/Qq and Qq/JJ

C. Jq/jq and jQ/jq

D. JQ/jq and Jq/jQ

Maize (Zea mays) contains 20 chromosomes in a diploid cell. How many chromosomes will be in each cell after the first and second division of meiosis?

If a heterozygous grey fruit fly is mated with a black-bodied fruit fly, what proportion of the offspring would be black?

A. 0 %

B. 25 %

C. 50 %

D. 100 %

In fruit flies (Drosophila melanogaster) grey body is dominant to black body and long wings are dominant to vestigial wings. Two flies heterozygous for both genes were crossed. What proportion of the offspring would be expected to have black bodies and long wings?

A. 1/2
B. 3/16
C. 1/4
D. 1/16

In a fruit fly experiment, grey body, normal winged (homozygous dominant) fruit flies were mated with black body, short winged (homozygous recessive) fruit flies. The F₁ dihybrid females were then used in a test cross. If the genes are always linked and no crossing over occurs, what would be the predicted ratio in the F₂ generation?

A. 9 : 3 : 3 : 1

B. 1 : 1 : 1 : 1

C. 3 : 1

D. 1 : 1

How do the concepts of gradualism and punctuated equilibrium differ?

A. The timing of evolution

B. The mechanism causing evolution

C. The sequence of evolutionary events

D. The reality of evolution

In a variety of tulips, V is the allele for variegated colour and C is the allele for compound flower. Which cross will give a 1:1:1:1 ratio of phenotypes in the offspring?
A. VvCc × VvCc
B. VVcc × vvCC
C. VvCc × vvCc
D. Vvcc × vvCc

When does an unequal division of cytoplasm occur?

A. During meiosis in the apical meristem
B. During the division of Sertoli cells into spermatozoa
C. During binary fission of eukaryotic cells
D. During meiosis in the human ovary

The genetic determination of dogs’ coats can be quite complex, with many different genes acting at the same time.

• The dominant allele E gives brown tones. The recessive allele e results in red tones.
• The colour intensity is due to another gene. The dominant allele B gives a dark colour, whereas the recessive allele b results in a light colour.

What would be the genotype of a light brown dog produced from a cross between a dark brown dog and a light red dog?

A. EEbb

B. EeBb

C. eeBb

D. Eebb

How many autosomes are there in a human sperm?
A. 1
B. 22
C. 23
D. 46

What is polygenic inheritance?
A. A character that is controlled by two or more genes
B. A character that is controlled by more than two copies of a gene
C. Inheriting more than two alleles of a gene
D. Inheriting a linked group of genes

What is a suspected heterozygous individual crossed with in a test cross?

A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous dominant
D. Heterozygous recessive

This is the cross that led to the discovery of non-Mendelian ratios in Morgan’s experiments with Drosophila.

Which is a recombinant genotype?

Male flies, heterozygous for both grey body and normal wings, were mated with black-bodied, vestigial-winged females. 2000 offspring were counted. The resulting percentage of each type of offspring is shown in the table below.

What conclusion can be drawn from the information given above?

A. The genes assort independently.
B. A mistake has been made.
C. The genes are linked.
D. The genes are on separate chromosomes.

What causes genetic variety in the formation of gametes during meiosis?

A. Crossing over in prophase I and random orientation of homologous chromosomes in metaphase I
B. Crossing over in metaphase I and random orientation of homologous chromosomes in metaphase II
C. Linkage of genes in prophase I and crossing over in metaphase I
D. Linkage of genes in metaphase I and random orientation of homologous chromosomes in metaphase II

The curly hair of the coat of Selkirk Rex cats is due to the presence of the allele SC.  These cats can either have tight curls or be moderately curly, whereas the coat of other cats is usually made of straight hair with no curls because of the allele SS.  Circles indicate female cats and squares indicate males.

What are the phenotypes of cats with these genotypes?

The statement is about the genetic control of cat coat colour.

In a cross between two double heterozygous tabby cats, what would the expected proportion of black offspring be?

A. 1 out of 16
B. 3 out of 16
C. 4 out of 16
D. 9 out of 16

The graph shows variations in beak size for the bird Geospiza fortis on an island in the Galápagos archipelago.

What evidence from the graph indicates that disruptive selection is occurring?

A. An intermediate beak size is less common.

B. Median beak size is the most common.

C. Smaller beaks are favoured.

D. Larger beaks are favoured.

Which gametes can result from the following crossover?