<u>Human activity</u>. The sixth mass extinction of of organisms caused by human actions potentially could go as far back as the late Pleistocene era (over 12,000 years ago.)
Answer:
A
Explanation:
a. contain checkpoints that determine if the cycle will continue.
b. help move chromosomes to the new daughter cells.
c. produce more chromosomes before the cell divides.
d. grow and produce enough cytoplasm to fill two cells.
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<em>The correct answer would be that G1 and G2 contain checkpoints that determine if the cycle will continue or otherwise.</em>
The cell cycle generally has three checkpoints that happen at G1, G2, and M phase of the cycle.
At G1 checkpoint, the integrity of the DNA of the cell is assessed to ensure that there are no damages and other conditions such as size and energy reserve are checked.
At G2 checkpoint, the cell is assessed for proper chromosome duplication to ensure that there are no mistakes or damages. The size of the cell and the amount of protein are also checked to ensure that the cell is ready for the active division phase.
At M checkpoint, correct attachment of the spindle fiber to the kinetochore of the chromosomes is checked. This checkpoint is also known as the spindle checkpoint and it happens towards the concluding phase of the metaphase stage.
<u>The correct option is therefore, A.</u>
Answer:
Crossing over
Explanation:
During prophase I of meiosis, homologous chromosomes pair to form bivalents. The chromatids of bivalents may form intimate contact points called chiasmata. At the chiasmata breakage may occur and exchange of chromatids segments between non sister chromatids may take place. This is crossing over ad results in new gene combinations causing variations.
Answer: Amount of sunlight absorbed
Explanation:
The amount of sunlight absorbed by the body affect the color of the individual. Rest all the factors that affects the color of the individual are genetic factors.
The person who absorbs more sunlight will have more melanin concentration or amount in their cells as as compared to the person who absorbs less sunlight.
Hence, the correct answer is option sunlight absorbed.