Answer:
Mutations of enzymes involved in nucleotide excision repair.
Explanation:
- Xeroderma pigmentosum is a genetic disorder and the person suffering from this disorder is sensitive to ultraviolet light due to the disability of the enzymes involved in nucleotide excision repair which prevents DNA damage caused by ultraviolet light.
- Thus, the individuals are sensitive to the exposure of UV and suffer severe problems when exposed to sunlight.
- The major cause of the disorder is the inability to repair DNA damage caused by exposure to sunlight due to the mutation in an enzyme involved in nucleotide excision repair.
- Nucleotide excision repair is a DNA repair process that can excise out single-stranded DNA that is damaged by UV.
- UV exposure leads to the addition of bulky adducts in the DNA known as thymine dimers. The enzymes of NER are involved in the removal of these adducts by excising out a segment of DNA that contains such lesions.
- However, in the case of XP, the mutations make this repair system non-functional or partially functional and thus, the individual becomes highly sensitive to UV exposure.
4. Large, circular lily pads are able to float on the water's surface.
Answer: cohesion
Cohesion mean that water attracted to another water. This force will make the water to form a surface tension in the lake. Water lily has a wide and thin leaf which makes it giving a low force per area. If the force applied on the surface is not bigger than surface tension, the leaf will stay float above the water. Surface tension also the reason water spider could walk on water.
5. The temperature of the water is about 5°C, while the temperature of the air is about 21°C.
Answer: heat capacity
Water has high heat capacity. High heat capacity mean that the water will not be easily become cold or hot. It will need more energy to increase/decrease the temperature of the water. This is why the water could keep its temperature much lower than the atmosphere. This will protect the organism inside the water from an extreme temperature change.
If an object has a net force acting on it, it will accelerate. The object will speed up, slow down or change direction. An unbalanced force<span> (net force) acting on an object changes its speed and/or direction of motion. An unbalanced force is an unopposed force that causes a change in motion. A net force = unbalanced force. </span><span>If however, the forces are balanced (in equilibrium) and there is no net force, the object will not accelerate and the velocity will remain constant. the source i found this answer is, https://www.mansfieldct.org/Schools/MMS/staff/hand/lawsunbalancedforce.htm
and the author of the source is , Mr. Hand</span>
