Biology iGCSE - Topic 3 - Notes - Reproduction & Inheritance

____ involves the fusion of a male and female gamete to produce a ____ that undergoes cell division and developed into an ____

What is GERMINATION

What are the three elements needed to facilitate germination and why

Secondary sexual characteristics

Females: oestrogen

Name 5 symptoms of oestrogen present in a female

Secondary sexual characteristics

Male: testosterone

Name 5 symptoms of testosterone present in a male

Menstrual cycle

The menstrual cycle lasts ____ days and the egg is usually released on day ____ (ovulation)

Developing embryo
The placenta allows diffusion of ___, ___ and ___ ___ from the mother's blood to the developing foetus of growth. ___ ___ and ___ from the foetus are passed into the mother's blood to be removed. It also takes one the production of ___

What am I describing?

An organism's reproductive cell (egg in female and sperm in males), which has half the number of chromosomes (23)

What am I describing?

The entire DNA of an organism

A structure found in the nucleus which is made up of a long strand of DNA

The different forms of the gene - humans have two alleles for each gene as they inherit one from each parent

Only one (out of two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed

Two copies are needed for it to be expressed and for the corresponding the phenotype to be observed

When both inherited alleles are the same (ie two dominant alleles or two recessive alleles)

When one of the inherited alleles is dominant and the other is recessive

The combination of alleles an individual has eg Aa

The physical characteristics that are observed in the individual eg eye colour. Phenotypic features are the result of polygenic (multiple genes) inheritance rather than single genes

When neither allele is dominant over the other, so both contribute to the phenotype eg. a white chicken and black chicken can have offspring that are speckled so the web is codominant