A3.1 - Diversity of organisms Flashcards
Which of the following could be a difference between the members of two distinct species
but could not be a difference between members of the same species?
A. Number of chromosomes.
B. Mutations.
C. Traits.
D. Genotypes
A. Number of chromosomes.
Which of the following is the correct binomial name for the Great white egret shown in the
image?
A. Ardea Alba
B. Ardea alba
C. ardea alba
D. ARDEA alba
B. Ardea alba
If two populations are separated by a geographical barrier such as a mountain range and
cannot interbreed, which reason on its own would be enough to classify them as two
separate species?
A. They could not interbreed if they were in the same location.
B. They are separate populations and therefore separate species.
C. All the individuals in both populations share the same traits.
D. There are minor morphological differences between the populations.
A. They could not interbreed if they were in the same location.
In relation to two distinct isolated populations, which technique might be used to decide if
they ae closely related in evolutionary terms?
A. Karyotyping.
B. Whole genome sequencing.
C. Autoradiography
D. Counting the number of chromosomes.
B. Whole genome sequencing.
The table shows the diploid chromosome number of a certain mammals, their approximate body mass in Kg and their genome size in Gbp.
Outline the meaning of the term genome size.
The genome is all the genetic information of an organism.
It is measured by the total amount of DNA, measured by the number of base pairs.
Note: In Eukaryotes,
“genome” usually refers to one copy of each autosome, plus one of
each sex chromosome X and Y (if it is present), the mitochondria DNA and the
chloroplast DNA (if present).
The table shows the diploid chromosome number of a certain mammals, their approximate body mass in Kg and their genome size in Gbp.
Explain why the diploid number of chromosomes is an even number for all species.
In a diploid cell, the chromosomes are in pairs (and there are two sex chromosomes.)
The table shows the diploid chromosome number of a certain mammals, their approximate body mass in Kg and their genome size in Gbp.
Suggest two reasons why the genome size has little variation between species and the
masses of mammals has wide variation.
Genome size is (virtually) constant within all members of a species because individuals only differ by small changes in base sequence, different alleles.
Members of a species have the same number of chromosomes / genes.
Body size is affected by the number of cells, the diet eaten by the animal, and age.
Body size is affected by inheritance of alleles but the difference in size between alleles is
very small; and so doesn’t change the genome size.
We don’t have as much data about whole genome sequences as we do about animal
masses.
NOTE: Award 2 marks for any 2 points made.
The table shows the diploid chromosome number of a certain mammals, their approximate body mass in Kg and their genome size in Gbp.
Discuss whether a larger genome size is caused by a larger number of chromosomes in a diploid cell.
The data does not indicate that a larger genome size has a larger (diploid) number of chromosomes.
For example, the largest genome size is 5.4Gbp in the African elephant, but the largest number of chromosomes is 78 in the European wolf
(Accept one mark for any relevant numerical example).
Chromosomes can have different lengths/ more DNA/a greater or smaller number of base pairs.
The size of chromosomes has more effect on chromosome number than genome size.
It is a small sample size/the sample is only mammals so the results have a limited reliability for generalising trends (induction)
NOTE: Award 2 marks for any 2 points made.
The table shows the diploid chromosome number of a certain mammals, their approximate
body mass in Kg and their genome size in Gbp.
Explain why two genomes of individuals from a single species would show less difference than two genomes of individuals from two different species. (2 marks)
Organisms of a single species may interbreed/separate species do not interbreed.
Any mutations in individual genomes can be inherited by their offspring, giving a single evolutionary pathway shared by all members of the species.
Mutations accumulated by two individuals of two separate species will be different.
The separate species will accumulate differences.
NOTE: Award 2 marks for any 2 points made.
There is evidence that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 in a common human ancestor. Outline the evidence that could support this hypothesis. (3 marks)
The banding pattern of human chromosome 2 closely matches primate chromosomes 12 and 13.
The banding patterns support the hypothesis of head-to-head fusion of chromosomes 12 and 13.
Human chromosome 12 has two centromeres but only one is active.
There is evidence of the remains of telomeres at the fusion point of chromosomes 12 and 13.
The great apes have a diploid number of 48, humans have a diploid number of 46.
Risso’s dolphin, (Grampus griseus) has a diploid chromosome number of 40, Common bottle-nose dolphins (Tursiops truncates) have a diploid number of 44. There have been reliable sightings of hybrid Risso’s and Bottle nose dolphins in the wild.
Suggest why such a hybridisation is very uncommon but is possible. (2 marks)
The two dolphins are each from a different genus.
The dolphins are in a different genus and so have genetic and morphological differences.
The haploid chromosome numbers of the two dolphins are 20 and 22.
Fertilisation of gametes would give a diploid chromosome number of the hybrid of 42.
The hybrid (zygote) would be able to grow by mitosis as it has an even diploid chromosome number
Pairing of chromosomes in mitosis would be possible in the hybrid animal/
NOTE: Any two points from this list would be awarded 2 marks.
Explain why the biological species concept cannot be precisely applied to Prokaryotes.
(2 marks).
The biological species concept requires members of a species to be able to breed and produce fertile offspring. / It assumes that two parents and sexual reproduction.
Bacteria cells don’t reproduce in this way, they divide by an asexual process of binary fission.
Prokaryotes have horizontal gene transfer. / Prokaryotes can exchange plasmids.
Bacteria even exchange genetic material between members of different species.
NOTE: Any two points from this list would be awarded 2 marks.
Outline a method using DNA analysis that can be used to determine the biodiversity of an
ecosystem.
(2 marks)
Environmental DNA can be sampled.
Analysis of the DNA can identify species in an ecosystem.
DNA analysis can produce barcodes.
NOTE: Any two points from this list would be awarded 2 marks.
Barcodes give quick and accurate identification of species.
