Every AQA A Level Biology Flaschard Flashcards
What is PRIMARY succession?
It is the process where pioneer species, such as lichens, colonize an area adapted to harsh conditions.
What happens after pioneer species die in PRIMARY succession?
They are decomposed by microorganisms, adding humus and eventually forming soil.
What occurs as the environment becomes suitable for more complex organisms in PRIMARY succession?
Soil becomes richer in minerals, allowing plants like shrubs to survive.
What is a climax community?
It is the final stage of succession, a self-sustaining stable community of organisms.
What are the stages of SUCCESSION?
A) Pioneer
B) Intermediate
C) Climax
D) Bare rock
E) Lichens
F) Small annual plants & lichens
G) Perennial herbs & grasses
H) Grasses, shrubs & shade-intolerant trees
I) Shade-tolerant trees
What is the MARK-RELEASE-RECAPTURE method?
A method used to count fast-moving or hidden animals by capturing, marking, and releasing them.
Why is the MARK-RELEASE-RECAPTURE method used?
To count fast-moving or hidden animals.
What is CONSERVATION?
The management of the earth’s resources, typically involving the management of succession.
Give an example of CONSERVATION.
Controlled burning of land is done to stop the formation of a climax community.
What is SECONDARY succession?
Succession that occurs in a previously colonized area where an existing community has been cleared.
What events can trigger SECONDARY succession?
Events like forest fires.
What is a RECESSIVE allele?
A characteristic expressed only if there is no dominant allele present.
What is required for a RECESSIVE allele to be expressed?
Two recessive alleles (homozygous recessive) must be present.
What is a CODOMINANT allele?
Both alleles are expressed equally, contributing to the phenotype.
What does PURE BREEDING mean?
A homozygous pair of alleles.
Define ALLELE.
An alternative form of a gene.
What is meant by HOMOZYGOUS?
Both alleles are dominant or both alleles are recessive.
What is meant by HETEROZYGOUS?
One allele is dominant and the other allele is recessive.
Describe the structure of bony fish gills.
They have 4 pairs of gills supported by arches, with multiple projections called gill filaments.
What are lamellae in bony fish gills?
Structures on gill filaments that help with gas exchange.
What points are assumed so the Hardy-Weinberg equation can be used?
No mutations occur to create new alleles. There is no movement of alleles into/out of the population by migration. The population is large. There is no selection = every allele has an equal chance of being passed to the next generation. Mating is random.
What is INTRAspecific competition and give examples of factors that affect it?
Factors that members of the SAME species compete for.
FACTORS = food, water, mates, shelter, minerals and light.
Describe an example of INTRAspecific competition.
Male robins maintain a large territory to support their families but in winter when food is short, they move to other males’ territories to obtain enough food to survive.
What is INTERspecific competition and give examples of factors that affect it?
When members of DIFFERENT species compete with one another for the same resources. This occurs most commonly when different species occupy the same niche.
