Answer:
<h2>Nuclues</h2>
Prokaryotes lack a defined nucleus (which is where DNA and RNA are stored in eukaryotic cells), mitochondria, ER, golgi apparatus, and so on. In addition to the lack of organelles, prokaryotic cells also lack a cytoskeleton.
Explanation:
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Answer:
1. genetic drift; 2. natural selection; 3. gene flow; 4. natural selection
Explanation:
<u>1. A fish net captures twenty fish, all who happened to have large spots:
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The mechanism of evolution that is playing out in this situation is most likely <u>genetic drift.</u> Genetic drift occurs when a random change occurs, resulting in the selection of a number of individuals by chance, rather than based on their level of fitness. The fish with large spots allele were selected against by chance, not necessarily because the fish with the small spot alleles were better fitted.
<u>2. Small spotted fish escape from predators better:</u>
The situation here is <u>natural selection</u>. The small spotted fish possess a greater fitness as they become well adapted to escaping from predators better than the large spotted fish, which gives confers on them a greater fitness to be selected for against the large spotted fish.
<u>3. 15 large spotted fish move into this population:</u>
The movement or introduction of new individuals i<u>
</u>nto a population is what is referred to as <u>gene flow</u> in evolution, which is another mechanism of evolution that changes the allele frequency of the original population.
<u>4. Fish-eating birds catch large spotted fish more easily:</u>
This is another example of natural selection. The small spotted fish possess a greater fitness which makes them not easily preyed upon by Fish-eating bird easily, compared to large spotted fish. <u>Natural selection</u> favors the fish with small spotted alleles against the large spotted fish, and as a result, more small spotted fish would survive and reproduce more offspring with the small spotted alleles compared to those with large spotted alleles.
Answer:
Diploid microspore mother cells divide by meiosis to form four haploid microspores. Each microspore develops into a pollen grain by mitosis.
Explanation:
Pollen grains contain the male gametes of a sexually reproducing plant. Pollen grains are haploid cells in nature produced by the meiotic division of microspore mother cells (located in the anther). The meiosis of these diploid (2n) microspore mother cells give rise to four haploid microspores. This process in plants is called microsporogenesis.
Each haploid microspore (n) develops into pollen grain called microgametophye (bearing male gamete) via mitotic division. During the pollen grain formation, a wall is formed around the microspores.
