Learn Genetics O/A-level

29/08/2023

20/05/2023

The human genome contains approximately
A. 17, 000 genes
B. 19, 000 genes
C. 21, 000 genes
D. 23, 000 genes

20/05/2023

Sonic hedgehog (SHH) gene was named after...

20/05/2023

The basic structural unit of gene is
A. Chromosome
B. Spliceosome
C. Nucleosome
D. DNA

16/08/2022

PROBLEM
A color-blind man married a normal woman. Their daughter, who was phenotypically normal, married a normal man and the couple produced three children: a normal boy, a color-blind boy, and a color-blind girl with Turner syndrome. Explain the origin of the color-blind girl with Turner syndrome.

FACTS AND CONCEPTS
1. Color blindness is caused by a recessive X-linked mutation, cb.
2. Turner syndrome is due to monosomy of the X chromosome (genotype XO). 3. Monosomy can arise from chromosome nondisjunction during mitosis or meiosis. 4. Mitotic nondisjunction in an XX individual can create a mosaic of XO and XX cells.

13/05/2022

Drosophila melanogaster is ideal to work with in the laboratory because:
A. it reproduces quickly
B. it is inexpensive to raise in the lab
C. it has only four pairs of chromosomes
D. all of the above
E. none of the above

24/02/2022

In a family with two children, what is the probability that:
(a) both are girls?
(b) one is a boy and one is a girl?

24/02/2022

In a family with three children, what is the probability that two are boys and one is a girl?

20/02/2022

What visible characteristics of chromosomes indicate that they have undergone crossing over during meiosis?

21/01/2022

Translation takes place:

A. in the nucleus of the cell
B. on ribosomes
C. outside the cell
D. on the endoplasmic reticulum
E. none of the above

21/01/2022

The largest gene characterized to date is:

A. 50,000 nucleotides in length
B. 500,000 nucleotides in length
C. 1,000,000 nucleotides in length
D. 2,500,000 nucleotides in length
E. 5,000,000 nucleotides in length

23/12/2021

The process of replication uses:

A.one strand of DNA to produce two strands of RNA
B.two strands of DNA to produce two strands of RNA
C.one strand of DNA to produce one strand of RNA
D.two strands of DNA to produce one strand of RNA.