Question 1
DNA replication can be defined as the process by which during cell division the DNA duplicates itself to several copies. In this process, the first step involves the unzipping of the double helix found in the DNA structure. This is done by the helicase enzyme, which breaks hydrogen bonds holding the DNA together. When separated the two DNA strands form a replication fork with a Y shape (Craig et al. 2014). This causes the strands to be oriented in different directions, forming the leading and the lagging strands. Once the two orientations are formed, a short RNA piece called primer binds the tip of the leading strand and acts as the commencing point for DNA Synthesis.
On the other hand, numerous RNA primers bind various points along the strand that lags. Following that, two types of replications occur: continuous replication for the leading strand (3’ to 5’ direction) and discontinuous replication for the lagging strand (5’ to 3’ direction). Once the matching up of A with T and C with G is done, the exonuclease enzyme strips away the primers. The new strand formed is then proofread to ensure no mistakes in the sequence and finally, the DNA ligase caps the sequence creating a double helix into the new DNA.
Question 2
The two major events that occur in each stage of mitosis are karyokinesis and cytokinesis. Karyokinesis involves the separation and distribution of the sister chromatids to a pair of identical daughter nuclei, whereas cytokinesis involves the division of the cytoplasm. It divides the cell into identical halves each having an identical nucleus.
Question 3
Question 4
Biological magnification is the process by which toxic substance are concentrated up the food chain. When this occurs the organisms at the lower, part of the food chain amasses a smaller portion than those on the higher level. For instance, when organisms consume other organisms below them in the food chain that have effects of toxicity in them, such as a bear eating fish, the toxic substances rise up the food chain (Craig et al. 2014).
Question 5
The harsh famine in Northern Africa could be explained to be brought about by ecological issues. This is caused by extreme environmental glitches that include desertification, deforestation, insect infestation, land erosion and degradation of wetlands. The human species in general in this area has been viewed to be highly irresponsible towards the environment, also affecting other species, hence further contributing to this problem. Survival has even become more difficult since more natural resources are exploited and the environment degraded.
Question 6
Loss of Biodiversity
The rapid increase in human population has led to the encroachment of human to the wildlife habitat. This has, as a result, led to the loss of animal habitat, instability, and climate change. With these consequences, animals are not able to adapt to the rapid change of environmental temperatures hence causing them to die.
This issue can be solved by protecting biodiversity. This includes adapting to environment-friendly products. The merit of this is that it ensures that the animal habitats are not only saved but also the environment is saved to avoid climate change and global warming.
Question 7
Some of the factors that influence biotic potential include reproduction frequency, age at reproduction, reproductive lifespan and a number of offspring produced. For instance, there are species that give birth to more offspring than the others give birth, e.g. ducks give birth to more ducklings than human to babies. When it comes to age, different species are capable of giving birth at different ages. Reproductive lifespan can also be considered in that there are animals with a very short reproductive span compared to others. For instance, the larger population of houseflies compared to elephants can be explained to be caused by the shorter and quicker reproductive lifespan and the age at the reproduction of houseflies to the longer span in elephants.
Question 8
Since the color, blindness is carried in the X-chromosomes, which is the only one found in men. There is a 50% chance of the son inheriting the faulty gene from the mother hence becoming colorblind. However, the daughter of the woman’s son is unlikely to be colorblind unless her father is color blind, which only retains her a 50% chance of carrying the gene.
Question 9
If both the man and woman have freckles but give birth to a child with no freckles, this means that the parents have the no freckle gene. Even though the freckles gene is dominant and active, the no freckle gene is a recessive one. This creates a likely chance of the parents giving birth to a child with no freckle. Assuming the F=Freckles and f=no freckles, Dad=Ff and Mom=Ff. When the sex chromosome split the child is likely to obtain ff=no freckles gene.
Question 10
Question 11
Sex-linked traits can be said to be traits from genes that are contained in the sex chromosomes. These could include traits like color blindness and sickle anemia. On the other hand, sex-influenced inheritance is the autosomal traits that are sex influenced. However, for the sex-influenced traits, its expression can be gender influenced. Such a trait includes baldness.
Question 12
1 – Autosomal dominant
2 – x-linked recessive
3 - Autosomal recessive
4 – x-linked dominant
Bonus question
Using the combination rule
[8! / 4! (4!)] / 48
= [40,320 / 576] / 65536
= 70/65536
= 35/32768
= 0.00107
References
Craig, N., Green, R., Greider, C., Cohen-Fix, O., Storz, G., & Wolberger, C. (2014). Molecular biology: principles of genome function. OUP Oxford.
