Answer:
<em>UV rays are highly injurious to living organisms since </em><em>DNA</em><em> </em><em>and</em><em> </em><em>proteins</em><em> </em><em>of</em><em> </em><em>living</em><em> </em><em>organisms</em><em> </em><em>preferentially</em><em> </em><em>absorb</em><em> </em><em>U.V</em><em> </em><em>rays</em><em> </em><em>and</em><em> </em><em>it's high</em><em> </em><em>energy</em><em> </em><em>breaks</em><em> </em><em>chemical</em><em> </em><em>bonds</em><em>. UV rays damage DNA and mutation may occur. It causes ageing of the skin, damage to skin cells and various types of skin cancers.</em>
Earthworms are delicate. Careful handling is important to
avoid damaging the internal organs.
Place the worm with the dorsal side up. Start the dissection
2 centimeters posterior the reproductive segment. Snip the skin above the dorsal blood
vessel ( near the posterior pin) through
the septa to the mouth.
Natural selection lead to different species when the squirrels were separated, some of them acquired traits better suited for their new environment. This allowed them to survive and reproduce better than others. Over time, each group evolved to display unique traits for their different environments until one species evolved into two.
Explanation:
The speciation in the squirrels due to the barrier in canyon occurred due to this. Such speciation is called allopatric speciation.
Speciation leads to formation of new species from the existing species due to change in their habitat or physical structure.
The squirrels on the two different side of canyon adapted to the habitat they are in. Their reproductive cycles, habitat and adaptation mode has become different due to the change in environment.
The species of squirrels became two as they reproduce and passed on the traits for survival in the environment which they had adapted.
The squirrels have become <em>reproductively isolated</em> also.
Genetic divergence takes place due to natural selection as squirrels arenow two different species.
Cells are the basic building blocks of life, which can join together to form tissues, while different groups of tissues join together to form organs. These organs are then connected together to form organ systems , such as the digestive system , which includes the stomach , esophagus , intestines and other organs .
