Unit 3 topic 1
This term describes the variety of all living organisms and the ecosystems in which they live.
What is biodiversity?
A species that has a disproportionately large effect on the structure of a community relative to its abundance.
What is a keystone species?
What is a nucleotide composed of in DNA
Deoxyribose sugar
Phosphate group
Nitrogenous base
define evolution
change in the genetic composition of a population during successive generations, which may result in the development of new species
This evolutionary mechanism involves random changes in allele frequency due to chance, especially in small populations.
What is genetic drift?
The total number of individuals that an environment can sustainably support is called this.
What is carrying capacity?
This term refers to the gradual change in species composition of a community over time.
What is ecological succession?
State two of the differences between DNA found in eukaryotes and prokaryotes.
what is the significance of conserved sequences
conserved sequences (e.g. mitochondrial DNA) are assumed to accumulate mutations at a constant rate over time and, therefore, provide a method for dating divergence.
recall an example of a transcription factor gene that regulates morphology
HOX transcription factor family
What are the three common assumptions of cladistics
This process describes how the nitrogen in dead organisms is converted into ammonia.
What is ammonification?
This process during meiosis increases genetic diversity by exchanging genetic material between homologous chromosomes.
What is crossing over (or recombination)?
describe natural selection
natural selection occurs when the pressures of environmental selection confer a selective advantage on a specific phenotype to enhance its survival (viability) and reproduction (fecundity)
identify the features of pioneer species
ability to fixate nitrogen, tolerance to extreme conditions, rapid germination of seeds, ability to photosynthesise
Contrast r and K reproductive strategies (3 differences required)
Any three correct
A mathematical model used to describe population growth without environmental constraints.
What is the exponential growth model (or J-shaped curve)?
State the steps to making recombinant DNA
- isolation of DNA, cutting of DNA (restriction enzymes)
-insertion of DNA fragment (plasmid vector)
-joining of DNA (DNA ligase)
-amplification of recombinant DNA (bacterial transformation)
Explain sympatric and parapatric speciation
Sympatric speciation is when two groups of the same species live in the same geographic location, but they evolve differently until they can no longer interbreed and are considered different species.
Parapatric speciation is when the populations that are diverging maintain a zone of contact and do not cease the exchange of genes completely. The species are spatially separated, but still exchange migrants. Nothing is stopping individuals from mixing and mating, but it doesn’t happen. The lower fitness of hybrids drives increased differentiation, eventually resulting in premating isolation.
what is the purpose of DNA polymerase
DNA polymerase forms new complementary strands using each original strand as a template to produce a copy. It adds complementary nucleotides to the exposed bases and also proofreads the strand.The direction of replication is 5’ to 3’.
White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-breasted nuthatch searches from the top of the trunk down. These hunting behaviors best illustrate which ecological concept?
resource partitioning
In a study of one population of phascogales, 72 animals were trapped and marked with ear tags. They were then released. One month later, fieldworkers examined 120 phascogale and found that 14 of these had ear tags. Use these figures to calculate the size of the phascogale population
617
three factors that regulate the phenotypic expression of genes
1. during transcription and translation (proteins that bind to specific DNA sequences)
2. through the products of other genes
3. via environmental exposure (consider the twin methodology in epigenetic studies)
Describe the three types of phenotypic selection
Directional, stabalising and disruptive plus suitable explanations
describe translation (include role of tRNA)
During translation:
The ribosome reads the mRNA codons.
The anticodon on the tRNA pairs with the complementary codon on the mRNA.
The ribosome catalyses the formation of a peptide bond between adjacent amino acids.
The tRNA then detaches and is reused to bring another amino acid.