Biology Paper 2 Flashcards
(52 cards)
Scientific names
> The first name is the Genus, written with a capital letter
The second name is the Species, written with a lowercase letter
The two names / the scientific name is underlined when written, in italics when printed
Classification class order
Kingdom → Phylum → Class → Order → Family → Genus → Species
Kids → Prefer → Cheese → Over → Fried → Green → Spinach
Extinction
Extinction is the permanent loss of all members of a species.
- New predators can wipe out populations of unsuspecting prey e.g. Dodos by humans
- New diseases
Species can become outcompeted e.g. red squirrels by grey squirrels
Why do we have an incomplete fossil record?
- Many early forms of life were soft-bodied
- The right conditions for fossilisation were rare
- There are many fossils still to be found
Fossil formation
- The organism dies and falls to the ground
The flesh rots and the skeleton becomes covered in sand or soil - Over millions of years, the skeleton becomes mineralised and turns to rock
- The rocks shift in the Earth with the fossil trapped inside
- Eventually, the fossil emerges as the rocks move and erosion takes place
Speciation
The process of a population becoming separated/ isolated and as a result of evolution/survival of the fittest, they develop into two separate species that can no longer interbreed with each other.
How can the population become isolated?:
> Geographical isolation
> Environmental isolation
Why did people reject Darwin’s theories at first?
- His ideas challenged the Church’s story of creation
- There was not enough discovered evidence to prove his theory
- Variety and inheritance could not be explained at the time
Charles Darwin evolution theories
He believed in the theory of evolution and survival of the fittest.
Jean Baptiste Lamarck evolution theory
he believed that animals acquired characteristics over their lifetime that could then be passed down to their offspring e.g. a giraffe could stretch its neck over time and its’ offspring would be born with a longer neck.
Mendel’s discovery
- monohybrid inheritance
- Using different types of pea plants, Mendel discovered that there were different units of inheritance, some of which were dominant over others.
Adult cell cloning
1 The nucleus of any adult body cell (except gametes) is fused with an empty egg cell.
2. These are stimulated to divide, forming an embryo.
3. The cloned embryo is implanted into an adult female who then gives birth
4. The offspring produced is genetically identical to the organism that provided the nucleus.
Genetic cloning in plants
Taking cuttings
> OR tissue culture:
A small tissue sample is taken from a parent plant
Tissue is grown in agar
Hormones and nutrients stimulate the plants into growing into new ones
Genetic engineering
Enzymes are used to isolate and ‘cut out’ the required gene from an organism
The gene is then inserted into a vector (usually a plasmid)
The vector is then used to insert the gene into the required cells
Genes are transferred to the cells at an early stage in their development - as the organism grows, it develops with the desired characteristics
Selective breeding
Organisms with desired characteristics are bred with each other to produce offspring with the desired traits. This process is repeated through generations.
Uses of selective breeding:
> disease-resistant crops > animals that produce more meat or milk > docile animals
> large, unusual or brightly coloured or heavily scented flowers
Evolution: survival of the fittest
there is variation within a population
> Reproduction means there are more offspring than the environment can support
> individuals with advantageous characteristics will survive longer and are more likely to breed
> the advantageous alleles are passed onto the next generations until the entire population possesses it
- However, this reduces variation
Carriers
someone who has one allele for a recessive disease so they do not show symptoms
cystic fibrosis
the body overproduces thick sticky mucus. It is recessive.
polydactyly
a disorder that means the child has extra fingers or toes. It is dominant
Phenotype
The expressed alleles e.g. brown eyes
Genotype
this describes the alleles present/ the genetic makeup of an individual
Heterozygous/ a Heterozygote
Someone with different alleles for a certain characteristic
Homozygous/ a Homozygote
Someone with two identical alleles for a characteristic
mutation
New forms of genes are created my random mutations in existing forms of genes
Mutations in genes can cause:
Slight change in shape but the substrate still fits the active site so function remains the same
Active site changes shape, enzyme does not work
Enzyme changes shape and fits a different substrate, catalyses a different reaction
How many bases code for 1 amino acid?
3
