Genes and chromosomes
Meiosis
Inheritance
Adaptations and ecosystems
Reproductive strategies
100
Alternative forms of a gene are called...
Alleles
100
Are the daughter cells of meiosis identical or different to their parent cell and why?
Different as they are haploid, their parent cell is diploid.
100
What is the type of inheritance called where both traits are equally dominant?
Co-dominance
100
What is the difference between biotic and abiotic factors?
Biotic factors are living components of an ecosystem. Abiotic factors are non-living components.
100
Name 2 types of asexual reproduction.
Two of: fission, budding, vegetative reproduction, spore formation, fragmentation or parthenogenesis.
200
Explain the bases pairing rule; which base pairs which which?
A and T
C and G
OR
Adenine and thymine
Cytosine and guanine
200
What are the main processes that lead to genetic variation in the gametes?
Crossing over (recombination) and independent assortment
200
When looking at a pedigree, how could you tell if it is more likely to be X-linked recessive or autosomal recessive?
X-linked recessive affects more males than females, autosomal affects both sexes equally
200
Define physiological adaptations
Features of the way an organism functions that increase their chances of survival (and reproduction).
200
What are two advantages of sexual reproduction?
Two of:
Offspring are genetically different from their parents.
Different genetics means some individuals are likely to survive if the environment changes.
Less competition for resources.
300
If an organism's diploid number was 108, what would their haploid number be?
54
300
During what phase of meiosis does crossing over occur?
Prophase 1
300
What are linked genes?
Genes located on the same chromosome, generally close together. They are inherited together.
300
What are adaptations?
Inherited characteristics that make an organism better suited to its environment and increase its changes of survival and reproduction.
300
What are two advantages of asexual reproduction?
Two of:
Only one parent needed, so don't have to spend time searching for a mate.
All genetically identical, so if well suited to the environment they all will be.
Can produce large number of offspring very quickly.
400
What is trisomy?
When there is an extra copy of one chromosome in an individual's cells.
400
What is this phase of Meiosis?
Metaphase 2
400
What phenotypic ratio would we expect if we crossed a homozygous recessive individual (rr) with a heterozygous individual (Rr)?
1:1
Half recessive phenotype, half dominant phenotype
400
Why is genetic diversity important for a species?
When conditions change in an environment so organisms may not be well suited and die, but if there is genetic diversity, some individuals should be able to survive and prevent the species becoming extinct.
400
What is the difference between gametes and spores in terms of what they need in order to produce new individuals?
Gametes need fertilising by another gamete in order to create a new individual. Spores contain all the genetic instruction instructions they need to produce a new plant when conditions are right.
500
Apart from the nucleus of cells, what other places can DNA be found in eukaryote cells?
In the mitochondria and the chloroplasts
500
Explain non-disjunction
This is where chromosomes fail to segregate, so one gamete will contain an extra chromosome while the other will be missing one.
500
What is a test cross?
When we cross an individual showing the dominant phenotype with a homozygous recessive individual to work out whether the dominant individual is homozygous dominant or heterozygous.
500
What is the difference between parasitism and amensalism?
In parasitism one species is benefited while the other is harmed, in amensalism one species is harmed while the other isn't affected either way.
500
Name the type of reproduction that allows fertilised eggs to developed into mature individuals (eg. in bees).
Parthenogenesis