Unit 3 Life on Earth Flashcards
What does biodiversity mean?
Biodiversity is the number of different species in a ecosystem
What is a ecosystem?
Natural biological unit made up of living and non living parts
What is a habitat?
The place where an organism lives
What is a community?
All the living organisms that live within a habitat
What is a population?
A group of living organisms of the same species eg a herd of sheep
what is a species?
a group of organisms that can produce offspring
What is a producer?
an organisms that produces its own food
what is a consumer?
an organism that gets energy by eating other organisms
what is a herbivore?
only eats plants
what is a carnivore?
only eats meat/other animals
what is a omnivore?
eats plants and animals/meat
what is a niche?
the role an organism plays within its ecosystem
what is interspecific competition?
competition between different species, for one or a few recourses they require
what is intraspecific competition?
competition within the same species, for all of the recourses they require
what competition is more intense?
intraspecific
what type of competition is more intense?
intraspecific competition
what are abiotic factors?
non living variables
- light intensity
- temperature
- soil pH
how do you measure abiotic factors and the precautions needed when using them?
- light meter : don’t shade it
- thermometer : wipe down the probe afterwards
- moisture probe : wipe down probe afterwards
what are biotic factors?
living factors
- predation
- disease
- food availability
how to sample biotic factors and precautions needed when doing it?
- quadrats : make sure to place quadrats randomly
- pitfall traps : must be covered so water can’t get in
what are indicator species?
species that indicate environment quality and pollution levels by their presence or absence
eg lichens, pollution indicators
what is the photosynthesis equation?
light energy
water+carbon dioxide——>oxygen+sugar
chlorophyll
Where is light absorbed in the cell?
the chlorophyll found in chloroplasts
what is the first stage of photosynthesis?
Light reactions
-light from sun captured in chlorophyll and converted to chemical energy to make ATP
- water is split to make hydrogen and oxygen
What is stage 2 of photosynthesis?
Carbon Fixation
-series of enzyme controlled reactions
-hydrogen and ATP from light reactions combine with carbon dioxide to make sugar
what ways can the sugar produced by photosynthesis be used?
-energy source (used in respiration)
-energy storage (starch)
-building material (cellulose)
what are the limiting factors of photosynthesis?
-carbon dioxide concentration
-light intensity
-temperature
how can energy be lost when being passed onto the organism that consumes it?
-heat
-movement
-undigested materials
what organisms use part of the lost energy from an organism?
decomposers
consume dead plants and animals
how much energy is lost within a food chain and how much is passed on?
90% is lost and only 10% is passed on
what does an increase in human population require?
an increase in food yield
food yield - volume of food frown/harvested
what are two common ways to increase crop yield?
pesticides - chemicals used to kill pests that damage crops
fertilisers - substance added to soil to increase fertility (increase nitrate content is soil)
what are the problems of pesticides?
could accumulate in bodies of organisms over time, as passed along the food chain toxicity builds up and can become lethal
what are pesticide alternatives?
genetically modified crops, biological control
what are examples of natural fertiliser?
compost, manure, ploughing clover
what are alternatives to fertilisers?
genetically modified
how do plants absorb nitrogen?
-nitrates dissolved in soil water are absorbed by roots
-nitrates produce amino acids and are synthesised into plant proteins
-animals consume plants or other organisms to obtain amino acids for protein synthesis
what are the problems of fertilisers?
fertilisers can leach into fresh water, that cause an algal bloom, this leads to a reduction in oxygen levels
what are the stages of algal bloom?
- fertilisers leach into fresh water
- increases algal population, causing algal bloom
- reduces light levels, killing aquatic plants
- bacteria feed on dead plants, and dead algae so bacteria increases
- bacteria use up lots of oxygen, reducing oxygen for other organisms
what are mutations?
a random change in a organisms genetic information
what are factors that increase mutation rates?
chemical - mustard gas, cigarette smoke
radiation - UK rays, X rays
what is an advantageous mutation?
some mutations can give an organism an advantage
what is a neutral word mutation?
mutations that can neither be an advantage nor disadvantage to the organisms survival
what are disadvantageous mutations?
is a disadvantage of the survival of the organism
what is natural selection?
natural selection is the survival of organisms best suited to their environment
also known as survival of the fittest
what is speciation?
the formation of a new species
what are the different barriers?
- geographical barrier
- ecological barrier
- reproductive barrier
how does speciation occur?
after a part of a population becomes isolated by a barrier different mutation occur in each of the sub populations, each sub population evolves until,they become so different they are two different species
