Cada pregunta de este test está cronometrada.
Which ONE of the following is the best definition of a species?
A population of similar animals which can interbreed.
A population of organisms which can breed to produce fertile offspring.
A community of organisms which can interbreed.
A population of organisms with similar characteristics.
What causes the genetic disorder where some males have the sex chromosomes XXY?
A sex-linked recessive allele.
Non-disjunction of chromosomes during meiosis.
Two sperm cells fertilise one ovum.
Crossing-over during meiosis.
The chromosome complement of a human individual who inherits an X chromosome from the father, is ...
44 and XX.
44 and XY.
46 and XX.
46 and XY.
Which ONE of the following is an example of artificial selection?
DDT resistance in mosquitoes.
The development of different species of tortoise from a common ancestor.
The decreasing effect of antibiotics on bacteria.
Breeding dairy cattle to increase milk production.
What percentage of adenine bases is present in a DNA molecule with 2 000 bases, if 400 of the bases are cytosine?
20%
30%
40%
60%
Two parents both have blood group A. Their child has blood group O. What is the best explanation for this pattern of inheritance?
The child has inherited the blood group directly from a grandparent.
The parents are homozygous for the blood group alleles.
The parents are heterozygous for the blood group alleles.
There has been a mutation in the blood group alleles.
