Topic 6: Inheritance, Variation and Evolution

What is sexual reproduction?

Involves the joining of male and female gametes, producing genetically different offspring.

What is asexual reproduction?

Involves one parent and no gametes, producing genetically identical offspring (clones).

What is meiosis?

A type of cell division that produces four genetically different gametes with half the normal number of chromosomes.

What are the advantages of sexual reproduction?

Produces variation, increases survival chances, allows selective breeding.

What are the advantages of asexual reproduction?

Only one parent needed, faster, uses less energy, produces many identical offspring in favourable conditions.

What is a gene?

A small section of DNA that codes for a specific protein.

What is the human genome?

The entire set of genetic material in a human, including all the genes.

What is a mutation?

A change in the DNA sequence that can affect protein structure and function.

What is a dominant allele?

An allele that is expressed if present; only one copy needed.

What is a recessive allele?

An allele that is only expressed if two copies are present.

What is genotype?

The combination of alleles an organism has.

What is phenotype?

The physical characteristics shown by an organism.

What causes cystic fibrosis?

A recessive allele; both parents must be carriers or affected.

What is embryonic screening?

Testing embryos for genetic disorders before implantation or birth.

What chromosomes determine sex in humans?

XX = female, XY = male.

What is variation?

Differences in characteristics caused by genes, the environment, or both.

What is evolution?

The gradual change in inherited characteristics of a population over time.

What is natural selection?

The process where organisms with advantageous traits survive and reproduce, passing traits on.

What is selective breeding?

Humans choosing organisms with desirable traits to reproduce.

What is genetic engineering?

Modifying an organism’s genome by introducing genes from another organism.

What is a GM crop?

A genetically modified plant with traits like pest resistance or higher yield.