Bio Quiz

The genotypes of two parents are HbA HbA and HbA HbS. What is the probability that a child of theirs would have sickle-cell trait (be carriers)?

50%

Dogs (Canis familiaris) have 78 chromosomes in their striated muscle cells. The number of chromosomes in a dog's skin cells is____ and in their gametes is___

78, 39

In some individuals, hemoglobin always contains the amino acid valine in place of a glutamic acid at one position in the protein. What is the most likely cause of this?

A base substitution in the hemoglobin gene.

A mutation in the CFTR gene causes cystic fibrosis. Which protein does this gene code for?

A chloride channel in the mucous membrane.

What is the difference between a gene and an allele?

A gene is a sequence of nucleotides in DNA or RNA while alleles are forms of a gene that slightly differ in their base sequence.

What is the set of alleles that an individual possesses?

A genotype

What does the genotype XHXh indicate?

A heterozygous female.

Sickle-cell anemia is a genetic disorder that occurs when an individual has two recessive alleles. Scientists have discovered that some people who are carriers of one allele for sickle-cell anemia are protected against malaria. Deduce which genotype would be the most advantageous to protect people against malaria without causing sickle-cell anemia.

Aa Heterozygous

In order to produce a karyotype for a fetus, there are two methods of obtaining fetal cells. Which method involves passing a needle into the abdomen in order to obtain a sample of amniotic fluid containing fetal cells?

Amniocentesis

What are the features of bacterial genetic material?

Bacterial genetic material is not associated with proteins, and consists of a DNA loop with a single copy of each gene.

Why does the proteome of a species contain a larger number of proteins than can be coded for by the genome of the same species?

Because there is differential and development-specific expression of genes.

Eukaryotic chromosomes are composed of:

DNA and histone proteins

What mutation causes sickle cell anaemia?

GAG is mutated to GTG.

Why is it not possible to be a carrier of Huntington's disease?

Huntington's is a dominant disease.

Which of the following is true about autosomes and sex chromosomes?

Males and females have the same type of autosomes but different sex chromosomes.

Some genes have only two alleles, other genes have many more variations. How are new alleles formed?

Mutation

Sometimes when gametes are formed, they can contain an extra copy of one chromosome. This leads to three copies of a particular chromosome. We call this trisomy. How does trisomy occur? (Give your answer as a maximum of two words).

Non Disjunction

What is a common cause for Down syndrome in humans?

Non-disjunction

Which is not likely to be the result of a base-substitution mutation in a gene?

Production of an altered protein with a completely new series of amino acids

Radiation, such as X-rays, or mutagenic chemicals can cause mutations and cancer. Which of the statements correctly describes their effect on mutations in genes?

Radiation and mutagenic chemicals increase chances of random mutations in genes.

Which of the statements about the chromosome number of a species is true?

The chromosome number tends to stay mostly unchanged in evolution of a species.

A gorilla cell has between 20,000 and 25,000 genes whereas an E. coli cell has approximately 4000 genes. Which of the following statements is true?

The gorilla genome is larger than the E. coli genome.

A student compared diploid chromosome numbers of several species with their genome size. Which of the conclusions about the chromosome number and genome size is true?

The size of the genome cannot be deduced from the number of chromosomes.

In sickle cell anaemia, a single base substitution occurs, causing sickled blood cells. The mutation occurs at the sixth codon of the Haemoglobin ß gene. Which base replaces adenine in the DNA of people with this mutation?

Thymine

Scientists were investigating the similarities and differences between base sequences of Homo sapiens and Homo neanderthalensis. A small sample of DNA was obtained from Neanderthal fossils and compared with sequences from humans. Which of the following biotechnological methods was likely used to carry out this comparison?

amplifying Homo neanderthalensis DNA sample using PCR

Which of these techniques was used by Cairns to measure the length of a DNA molecule?

autoradiography technique with radioactive isotopes

Karyograms are used to deduce sex and diagnose genetic diseases in humans. What would not be determined from a karyogram?

base substitution in a gene on chromosome 13

Be able to identify homologous chromosomes

k

What name is given to the exact position of a gene on a chromosome? (Answer with one word.)

locus

The nuclear explosion at Chernobyl power station in 1986 caused an increase in cancers in surrounding areas. Which cancer was seen to increase dramatically in children following the explosion? (Answer with one word.)

thyroid

Fertilisation occurs when a haploid sperm meets a haploid egg. The resulting cell is a diploid cell. What name do we give this diploid cell? (Answer with one word.)

zygote