Biology (A)

Vocabulary

allele

An alternative form of a gene.

asexual reproduction

A form of reproduction in which a new individual is created by only one parent.

binary fission

An asexual form of reproduction where a cell splits into two daughter cells.

crossing-over

Exchange of DNA segments between homologous chromosomes; occurs during prophase I of meiosis.

cross-pollination

Sexual reproduction in plants where sperm from the pollen of one flower is received by the ovary of another flower.

diploid

When a cell has two sets of chromosomes.

gametes

Cells involved in sexual reproduction; typically egg and sperm cells.

gonads

Organ that produces gametes, such as the ovaries and testes.

haploid

When a cell has only one set of chromosomes, typical of a gamete.

internal fertilization

Reproduction occurs through the internal deposit of gametes.

external fertilization

Reproduction where the eggs are fertilized outside the body.

meiosis

Nuclear division that results in haploid gametes.

ovaries

Female gonads in animals that produce eggs.

parthenogenesis

Reproduction where an unfertilized egg develops into a new individual.

sexual reproduction

Reproduction where gametes from two parents combine to make an individual with an unique set of genes.

sister chromatids

Two genetically identical chromosome segments that form after DNA replication.

testes

Male gonads in animals that produce sperm.

zygote

Single cell that is formed after the fertilization of an egg; the first cell of a new organism.