All of BIOLOGY PAPER 2 in 20 mins - GCSE Science Revision Mindmap 9-1 AQA

Chapter 1: Intro

Different types of contraception: physical methods and hormonal methods
- Examples: pill, patch
Fertility treatments available for couples struggling to conceive
- Artificial insemination (AI): collecting and implanting sperm
- In vitro fertilization (IVF): fertilizing an egg outside the body and implanting it into the woman
Other fertility treatments:
- FSH and LH therapy for hormone deficiencies
- Surrogacy: using another woman's uterus to carry the baby
- Egg donation or ovary transplant
Ethical questions surrounding IVF and playing God

Plants have hormones that regulate growth and responses to stimuli
Phototropism: stems grow towards light, geotropism: roots grow towards the ground, hydrotropism: roots grow towards water
Auxins are the main hormones responsible for growth and inhibition
Auxin's role in phototropism and geotropism
- In shoots, auxin collects on the bottom side, causing the stem to curve upwards towards light (positive phototropism)
- In roots, auxin collects on the bottom side, inhibiting growth and causing the root to bend downwards (negative geotropism)
Other plant hormones:
- Ethene: used to ripen fruits
- Gibberellins: promote flowering and increase fruit size

Two methods of reproduction: asexual and sexual
Asexual reproduction: cloning, no genetic variation between parents and offspring
Sexual reproduction: involves gametes (haploid cells) that combine to form a diploid cell with genetic variation
Gametes are produced through meiosis, a process involving chromosome duplication, crossing over, and cell division

DNA is a polymer with four bases: A, T, C, and G
Triplets of these bases are associated with amino acids
DNA is unzipped and copied by RNA, which carries the code to ribosomes for protein synthesis
Genome refers to all the DNA in an organism
DNA has a double helix structure with bases in between
Genes are specific parts of DNA that code for proteins

Variation is achieved through different forms of genes called alleles
Genotype refers to the gene combination, phenotype refers to the expressed characteristic
Punnett square is used to determine the possible genotypes and phenotypes of offspring
Dominant alleles mask the effects of recessive alleles
Homozygous alleles are the same, heterozygous alleles are different
Some disorders can be passed down genetically, such as cystic fibrosis

Genetic engineering involves changing a gene in a chromosome and inserting it into an organism using a vector (bacteria or virus)
Genetically modified (GM) crops are created through genetic engineering
Variation can be caused by both genes and the environment
Selective breeding is a method of amplifying desired traits over generations

Darwin's theory of evolution: random mutations between generations lead to variation in offspring
- Offspring better suited to the environment are more likely to survive and reproduce (survival of the fittest)
Lamarck's theory: environment leads to changes in genes
- Example of giraffes stretching their necks and passing on longer necks to offspring
DNA has the ability to turn genes on and off, allowing for changes in response to the environment
- Example of blind mackerel in a cave regaining functional eyes after breeding with normal mackerel

Protein shape determines function
Cloning involves taking the nucleus from a normal cell and inserting it into an egg
Cloned organisms, like Dolly the sheep, have shorter lifespans

Ecosystem: interactions between living (biotic) and non-living (abiotic) parts of an environment
Habitat: area where an organism lives
Community: multiple species in the same ecosystem
Population: number of individuals of a species

Predator-prey relationships: changes in prey population affect predator population and vice versa
If prey population decreases, predator population also decreases due to reduced food availability

Sampling used to estimate population of a species in an area or habitat
Quadrat: randomly placed in a field to sample a portion of the area
- Multiplying the sample by the whole area gives an estimate of the population
Transect: line along which a quadrat is moved to observe changes in population density over a distance
Population variation can be influenced by biotic (living) or abiotic (non-living) factors

Carbon cycle: plants absorb CO2 for photosynthesis, respiration releases CO2 into the atmosphere
Bacteria involved in decay produce CO2, which can also be stored in the ground as fossil fuels
Combustion of fossil fuels releases CO2
Water cycle: evaporation, condensation (cloud formation), precipitation (rain)

Linnaeus classification system: kingdom, phylum, class, order, family, genus, species
Binomial system: using genus and species to give organisms a two-name Latin name
Woese classification system: archaea, bacteria, eukaryota (organisms with DNA in a nucleus)
Biodiversity: range of different organisms and species in an ecosystem

Human activities can negatively affect biodiversity
Farming, building, deforestation, and pollution (e.g., fertilizer runoff) can harm biodiversity
Eutrophication: excessive fertilizer runoff leading to algae blooms, oxygen depletion, and fish death
Acid rain caused by release of sulfur oxides and