topic 5 - on the wild side Flashcards
ecosystem definition
all the organisms living in a particular area, as well as all the non living elements of that particular environment
community definition
all of the populations of all the organisms living in a particular habitat at a particular time
population definition
all of the organisms of a particular species living in a particular habitat at a particular time
habitat definition
the place where an organism lives
examples of biotic factors
- availability of food: more food means organisms have a higher chance of surviving and reproducing thus populations can increase
- new predators: ecosystem may become unbalanced
- new pathogens: no immunity or resistance so populations may die out
- competition
examples of abiotic factors
- light intensity
- temperature
- moisture levels
- wind direction and intensity
what is ecological niche
- the species particular role in a habitat
- consists of its biotic and abiotic factors within the environment
- species distribution and abundance depends on the number and type of ecological niches available
what is the niche concept
states that only one organism can occupy each niche in a given habitat at a given time - if two species have a niche that overlaps, the best adapted will out compete the others in surviving to reproduce
succession definition
the change in species inhabiting an area over time. brought about by changes to the environment made by organisms colonising it themselves
when does primary and secondary succession occur?
primary: when an area previously devoid of life is first colonised by communities of organisms - soil must be established before more complex organisms can grow
secondary: occurs with existing soil that is clear of vegetation. this may occur after an event such as a forest fire
what are pioneer species and what do they do
- give an example
- the area is first colonised by pioneer species , which are adapted to survive in harsh conditions
eg lichen - these species can penetrate rock surface and break it down into grains.
what is humus
- as organisms die, they are decomposed by microorganisms, thus adding humus which is the organic component of soil
- this leads to the formation of soil, which makes the environment suitable for complex organisms
what is a climax community
- the most productive, self sustaining and stable community of organisms that the environment can support, usually with one or two species
speciation definition
when two reproductively isolated organisms can no longer interbreed to produce fertile offspring
chloroplast structure
- stacks of thylakoid membranes, called grana, which contain chlorophyll, arranged as photosystems. this is the site of the light dependant stage of photosynthesis
- contains stoma, which is the fluid surrounding the grana. stoma contains all the enzymes required for the light independent stage
- chloroplast envelope: controls movement of substances
- starch granules: store products of photosynthesis
net primary productivity (NPP) definition
the rate at which energy from the sun is converted into the organic molecules that make up new plant biomass
why is some energy lost at each trophic level?
- undigested matter
- respiration
- metabolic waste products eg urea
how is chloroplast structure related to its function
chloroplast envelope: double membrane which encloses chloroplast, keeps all components needed for photosynthesis close together. transport proteins inside inner membrane control flow of molecules between stroma and cytoplasm
stroma: gel like fluid which contains enzymes that catalyse the reactions for photosynthesis
DNA: contains genes which code for some proteins used in photosynthesis
Ribosomes: enable translation of proteins
thylakoid membrane: space between the two membranes known as the thylakoid space, in which conditions differ from stroma eg so a protein gradient can be developed. the space has a very small volume so protein gradient can develop quickly
grana: large surface area for maximum light absorption. also provide more membrane area for proteins such as electron carriers and ATP synthase enzymes, to enable the production of ATP
photosystems: two types = 1 and 2 which contain a different combination of photosynthetic pigments. each photosystem absorbs lights of a different wavelength, maximising light absorption.
photosynthesis equation
co2 + water = glucose + oxygen
why is ATP required by all living organisms
- for building new molecules from the products of digestion during anabolic reactions
- to move substances across cell membranes in active transport or to move substances within cells
- for muscle contraction
- in the conduction of nerve impulses
describe ATP’s structure
- it is a type of nucleic acid
- it is a phosphorylated nucleotide, consisting of a nitrogenous base (adenine), a sugar (ribose) and three phosphate groups
how are ADP and AMP created
ADP: removal of one phosphate from ATP
AMP: removal of two phosphates from ATP
how is ATP produced
what is the equation
- is produced during respiration by the addition of inorganic phosphate (Pi) to adenosine diphosphate (ADP).
ADP + Pi = ATP - the breakdown of glucose in respiration releases the energy needed to phosphorylate ADP
the removal of a phosphate group is known as…
dephosphorylation
what does the hydrolysis of ATP release
what is the equation
what is it catalysed by
- releases an inorganic phosphate as well as a small amount of energy which can be used by the cell
- ATP = ADP + Pi
- catalysed by the enzyme ATPase
- the ADP and inorganic phosphate produced by the hydrolysis of ATP can be recycled to make more ATP
- ADP + Pi = ATP
what are the two distinct stages of photosynthesis and where do they take place
- the light dependant reactions (rely on light directly)
- the light-independent reactions (rely on the products of light-dependant reactions)
- both take place within the chloroplast
- the light-dependent reactions take place across the thylakoid membrane
- light independent reactions take place in the stroma
what can the products of photosynthesis be used for
glycerate 3-phosphate (GP) is used to produce…
1. amino acids which can be used for protein synthesis
2. fatty acids which form the tails of lipid molecules
glyceraldehyde 3-phosphate (GALP) is used to produce…
1.hexose sugars which can be converted into sucrose for transport in the phloem or joined together to make starch and cellulose
2. glycerol for building lipid molecules
3. nucleic acids which form the basis of DNA and RNA
primary productivity definition
the rate at which producers convert light energy into chemical energy
gross primary productivity definition
the rate at which chemical energy is converted is converted into carbohydrates during photosynthesis in plants
NPP equation
NPP = GPP - R
net productivity
rate at which energy is converted into biomass in the body of a consumer
why is energy lost in producers
- light passes through leaves
- light is reflected away
- light hits non photosynthetic parts of a plant eg bark
- light is a mixture of wavelengths and only certain wavelengths are absorbed in photosynthesis
- release of energy in respiration
energy efficiency equation
energy efficiency = (net productivity divided by energy received) times 100
how does evolution via natural selection work
- variety of phenotypes exist within a population due to random mutation
- an environmental change occurs and a result selection pressure changes
- some individuals possess advantageous alleles which give them a selective advantage and allow them to survive and reproduce
- advantageous alleles are passed on to their offspring
- over time, frequency of alleles in a population change
what is allopatric speciation and what does it lead to
- occurs when populations of a species become separated from each other by geographical barriers
- this leads to no gene flow taking place, which changes allele frequencies. if enough change occurs between the two populations then they eventually will no longer be able to breed with each other and produce fertile offspring and so are SEPARATE SPECIES
what is sympatric speciation and what does it lead to ?
- isolation caused by non-geographic factors such as seasonal and behavioural.
- leads to SEPARATE SPECIES
how are theories validated by the scientific community
- reading scientific journals: journals will be read and evaluated by many other scientists working the field of study (peer review) and published studies can be repeated to check that their results are reliable
- attending scientific conferences: scientists can present their findings for questions and discussion
what evidence do we have for evolution
- the fossil record
- real life observations eg antibiotic resistance
- molecular evidence
how can we find evidence from protein sequences
- this is called proteomics
- as the order of amino acids is determined by the DNA base sequence of the gene that codes for a protein, amino acid sequences can be used to determine evolutionary relationships in the same way as DNA sequences.
how can we find evidence from gene sequences
- this is genomics
- the level of similarity between base sequences can give a measure of how long ago two species diverged from each other during speciation eg genes with similar base sequences are likely to have diverged recently