biology Flashcards
what is a species?
organisms that can produce fertile offspring
what is biodiversity?
different plants and animals living on earth
what is an ecosystem?
habitat and community
what is a niche?
The role an organism plays within a community
what is grazing?
to eat on growing grass or herbs
what are abiotic factors?
soil moisture, light intensity, pH level, oxygen concentration, temperature
what are indicator species?
species that by their presence or absence indicate the levels of pollution
why may the biodiversity on a field be low?
few species of plants arent able to successfully compete against others in the ecosystem
what is photosynthesis?
green plants and other organisms transfer light energy into chemical energy
what are biotic factors?
competion, predation, disease, food availability, grazing
what is a control variable?
what you can change in an experiment
what is an independent variable?
the thing that you don’t change
what is a dependent variable?
what you measure in an experiment
what is a pyramid of numbers?
it shows the population of number at each feeding level in a food chain
what is a pyramid of energy?
the energy content at each feeding level. it shows the transfer of energy from one level to another.
what does the increase of human population require?
an increase in food yield which may involve fertilisers and pesticides
what are fertilisers?
chemicals such as nitrates which increase crop yield
what happens to plants and animals when they reduce crop yield?
they are killed by pesticides
how are fertilisers used?
they’re added to the soil to increase the nitrate content of the soil
what do nitrates produce?
amino acids which are synthesised into plant proteins
what do animals eat to obtain amino acids?
plants or other animals
what are alternatives fertilisers?
genetically modified crops can be used to reduce using fertilisers
what are pesticides?
the are sprayed onto crops and can accumulate in the bodies of organisms over time
what happens when organisms accumulated with pesticides are passed along food chains?
toxicity increases and can reach lethal levels
what are alternatives to pesticides?
gm crops, psychological control
what is natural selection?
survival of the fittest
what is speciation?
the evolutionary process in which a new species forms
