Year 10 Science: Genetics and Evolution

Allele

Different versions of a gene

Chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule

Diploid Cell

Cell with two sets of chromosomes (2n).

Haploid Cell

Cell with one set of chromosomes (n).

Gene

Segment of DNA coding for a trait.

Genotype

Genetic makeup of an organism (e.g. AA, Aa or aa)

Phenotype

Observable characteristics of an organism

Homozygous

Having two identical alleles for a trait (e.g. AA or aa)

Heterozygous

Having two different alleles for a trait (e.g. Aa)

Meiosis

Sex cell division producing haploid gametes

Mitosis

Normal cell division producing two identical diploid cells

Mutation

Change in DNA sequence affecting genetic information.

Fertilisation

Union of sperm and egg to form zygote

Embryo

A fertilised egg in the first eight weeks after conception

Foetus

Developing human after eight weeks of pregnancy

Gamete

Reproductive cell (sperm or egg)

Continuous Variation

Range of traits with no distinct categories

Discrete Variation

Traits that fall into distinct categories

Selective Breeding

Choosing parents with desired traits for offspring

Punnet Square

Diagram predicting genetic variation in offspring

Dominant

Allele that expresses phenotype in heterozygous condition (e.g. A)

Recessive

Allele that expresses phenotype only in homozygous condition (e.g. a)

Cervix

Narrow passage connecting uterus and vagina

Ovary

Female reproductive organ producing eggs

Oviduct/Fallopian Tube

Tube transporting eggs from ovary to uterus

Uterus/Womb

Organ where embryo develops during pregnancy

Vagina

Canal leading from cervix to external genitalia

Penis

Male reproductive organ for sperm delivery

Scrotum

Pouch containing testes in males

Testes (Testis, singular)

Male reproductive organs producing sperm and hormones

Sperm Duct

Tube transporting sperm from testes to urethra

Urethra

Tube carrying urine and sperm out of body

Prostate Gland

Gland producing seminal fluid in males

Zygote

Fertilised egg cell formed after fertilisation