Biology Genetics and Reproduction

Study Notes

DNA

DNA has a double helix structure, with two spirals.
DNA's structure is made up of base pairs, which represent the genetic code.
DNA is found in the nucleus of an animal cell.
Chromosomes are found in the nucleus of the cell.
Genes are sections of a chromosome and made up of DNA strands.

Genome

The genome is the entire genetic material within an organism.
Every organism has a unique genome.

Sexual reproduction

Sexual reproduction involves two parents.
Meiosis produces gametes.
Offspring are genetically different from parents due to a mixture of genetic material.

Asexual Reproduction

Asexual reproduction involves one parent.
Asexual reproduction produces genetically identical offspring through mitosis.
Asexual reproduction is common in plants.

Meiosis

Meiosis is cell division in which a cell divides into four gametes.
Cells duplicate their DNA before division.
During meiosis, chromosomes line up in the centre of the cell and then are pulled apart to opposite sides.
The cell divides again, forming four gametes.
Gametes have half the amount of DNA needed.

Genetic Diagrams and Variation

Genetic diagrams show the possible combinations of chromosomes and genes that offspring can inherit.
Punnett squares are used to show the possible combinations of alleles from each parent.
Sex chromosomes determine the gender of an offspring.
Females have XX chromosomes.
Males have XY chromosomes.
There is a 50/50 chance of an offspring being male or female.
Genetic diagrams can be used to determine phenotypes, or physical characteristics, of offspring with examples including eye colour.
Dominant alleles are strong and will determine a characteristic, while recessive alleles are weaker.

Variation

Genetic variation occurs due to differences in genes and alleles between organisms.
Genetic variation can be caused by mutations, which can lead to disorders like cystic fibrosis and polycystic kidney disease.
Environmental variation can also cause changes in organisms by altering their phenotypes, which are physical characteristics.
Differences in diet and exercise levels can affect the development of identical twins.

Evolution

Speciation is the process by which a new species forms.
Extinction is the complete disappearance of a species.
Darwin's Theory of Evolution is also known as Natural Selection.
Natural selection is the process by which organisms with more advantageous traits are more likely to survive and reproduce.
Evolution involves organisms developing and evolving into new species.
Factors that can cause extinction: environmental changes, new predators, disease, competition for food or shelter.

Classification

The three domain system groups organisms into three domains: Archaea, Bacteria and Eukarya.
Archaea are primitive bacteria.
Bacteria are more advanced bacteria.
Eukarya includes fungi, plants, animals and protists.
Classification helps us to understand the relationship between organisms and their evolutionary history.
Organisms are classified into seven levels, starting with Kingdom: Kingdom, Phylum, Class, Order, Family, Genus, Species.
You can use a mnemonic to remember the seven levels of classification.

Description

Explore the fascinating world of genetics and reproduction through this quiz. Learn about DNA structure, genomes, sexual and asexual reproduction, and the process of meiosis. Test your understanding of how genetic material is passed on and the differences between reproductive strategies.