IB Biology Topics 3.1 and 3.2 (Genetics)

The image shows a karyogram. What information can be determined from this karyogram?

• The sex is female.

• The haploid number is 54.

• Disjunction occurred during meiosis.

• The species is not human.

Tags

NGSS.HS-LS3-1

What distinguishes an allele from a gene?

• An allele is made of RNA.

• An allele is shorter.

• An allele is a variety of a gene.

• An allele cannot be transferred during genetic modification.

Which is a characteristic of the haploid number of eukaryotic chromosomes?

• It doubles in mitosis.

• It is fixed for each species.

• It is an even number for all species.

• It is positively correlated with an animal's mass.

The diploid number of chromosomes in humans (Homo sapiens) is 46 and the diploid number of chromosomes in rice (Oryza sativa) is 24. What does this indicate about diploid chromosome numbers?

• Plant species have a lower diploid number of chromosomes in animals.

• Members of a species have the same diploid number of chromosomes.

• The evolutionary progress of species is determined by the diploid number of chromosomes.

• The complexity of the organisms is correlated to the diploid number of chromosomes.

What is characteristic of homologous chromosomes?

• They have an identical DNA sequence.

• They are of the same length in karyograms.

• They form pairs in prokaryotes.

• They carry the same alleles.

What is the effect of dominant alleles?

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.

• I only

• I and II only

• I and III only

• I, II and III

Tags

NGSS.HS-LS4-3

What is a possible source of the chromosomes used for pre-natal karyotype diagnosis?

• The mother's lymphocytes.

• The mother's cheek cells.

• The cells from the chorionic villi.

• The fetal hair root cells.

What causes the presence of three chromosomes 21 in Down syndrome?

• Crossing over

• Allele change

• Non-disjunction

• Gene mutation

Tags

NGSS.HS-LS3-2

What is a characteristic of the human Y chromosome?

• It is made of DNA and histones covered by phospholipids.

• It contains some genes that are not present on the X chromosome.

• It is the largest chromosome in the human karyotype.

• It has a condensed length of approximately 100 µm.

What is the composition of eukaryotic chromosomes?

• DNA only

• DNA and ribose

• DNA and RNA

• DNA and proteins