Variation Flashcards
what is a species?
a group of organisms with similar features that distinguish them from other organisms
what is biodiversity?
the variety of living things, their relationships, and the ecosystems they form
why is it important for ecosystems to have high levels of biodiversity?
ecosystems with high levels of biodiversity are more able to survive change, because there is a greater chance of one of the species having features that enable it to adapt to change
what is classification?
the way that scientists group organisms, for example into a species
what is variation?
the range of characteristics across individuals of the same group
what is an ecosystem?
a community of organisms along with the non-living components (air, water, soil)
continuous variation
any feature that changes gradually over a range of values
discontinuous variation
features with a limited number of values
what is correlation
how well sets of data are linked; high correlation shows that there is a strong link between two sets of data
what is inbreeding?
breeding with close relatives
why is variation important to living organisms
variation in a population gives certain organisms with more favourable features a survival advantage. when these organisms reproduce, the feature is issued on to offspring
what causes variation?
- the environment you’re in
2. inheritance and genetics
why are offspring different?
parents pass on genetic information to their offspring in the nucleus of their sex cells. the offspring inherit one set of information from the mother’s egg cell nucleus and one set from the father’s sperm cell nucleus.
what is selective breeding?
selecting organisms with desirable features and use these to breed from
why do farmers use selective breeding?
ultimately helps farmers make larger profits bu producing higher quality products
what is natural selection?
process by which characteristics that can be passed on in genes become more common in a population over many generations if they help the organism survive
what did Charle Darwin conclude?
- all organisms produce more offspring than is needed
- organisms have a fairly constant population size
- there is a wide range of features within a species
- some variations are inherited by the offspring
what is a genome?
a genome is the DNA of a particular organism, for example a human genome
describe the shape of DNA
a DNA molecule consists of two strands that wind around each other to form a helix
where is DNA found?
in every nucleus of every living organism
how much DNA is in each cell?
approximately two metres
what does DNA do?
it carries the code for making all the proteins that contribute to the characteristics of every individual
what are genes?
a gene is a section of DNA that is responsible for producing a particular protein that contributes to a particular characteristic. such as eye colour
what does the nucleus contain?
the cell’s chromosomes
what is mutation
a change in a DNA sequence
how many single chromosomes does a human sperm cell and egg cell each contain?
23
what is a chromosome?
thread-like strands of DNA that carry genetic information
what are the seven characteristics of living organisms
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
what do viruses do?
enter cells and use the cell’s reproductive machinery to make new ones
what does bacteria do?
have a loop of DNA
what does fungi do?
causes mild disorder in humans
what are protoctists?
single-called organisms
what are four primary defences of the body that prevent pathogens from entering?
blood clotting
skin
mucus
tears
which cells make up the body’s immune system?
white blood cells
B-cells
T-cells
phagocytes
what conditions do bacteria need to grow?
oxygen
warmth
food
water
