Which of these pairs are both gametes?
Sperm and ovum
Ovum and zygote
Zygote and sperm
Which description best describes DNA?
A double helix made of bases
A monomer which carries the genetic code
A polymer made of nucleotides
Which pair of sex chromosomes shows a human female?
YY
XY
XX
How many chromosomes do gametes have?
Half the number that are in body cells
The same number as are in body cells
Twice the number that is in body cells.
What is the difference between an allele and a gene?
A gene is one of two copies of an allele in a pair of chromosomes.
An allele is one of two copies of a gene in a pair of chromosomes.
Allele and gene are two names for the same thing.
In the genetic cross Ee × Ee, what percentage of offspring are carriers?
25%
50%
75%
How many chromosomes do humans have?
2
23
46
What does heterozygous mean?
The two alleles are different genetic variants
The two alleles are the same genetic variant
The two alleles are both dominant
Why is a Punnett square useful?
It can predict the probabilities of each genotype in the offspring of a cross.
It can show how a particular feature is passed down the generations.
It shows information about phenotypes but not genotypes.
What does homozygous mean?