Answer:
30
Explanation:
The seed of an angiosperm is formed as a result of fertilization (fusion of sperm in pollens and the ova from ovary). According to the question, the cells of the seed which will grow into the plant contains 20 chromosomes. Seeds of angiosperms contain a tissue called ENDOSPERM that forms as a result of the unique DOUBLE FERTILIZATION in angiosperms. It occurs when one haploid sperm cell fuses with two haploid polar nuclei to form a triploid endospermic structure that serves as food for the growing embryo in the seed.
Now based on the above explanation, the diploid plant cell with 20 chromosomes will have 10 chromosomes (half as much) in its gametes as a result of meiosis. This 10 chromosomes in each gamete (sperm and ovum) fuses to form a diploid zygote with 20 chromosomes, while one haploid sperm cell (10 chromosomes) also fuses with two haploid polar nuclei (10 chromosomes each) to form a triploid endosperm with 30 chromosomes i.e. 10+10+10.
Answer:
1. Evolution can be defined as the gradual development of an organism creating diversity.
2. A common misconception is that Homosapiens are descendants of Apes.
3. analogous structures are features of different species that are similar in function, but not necessarily in structure; such as bird wings and insect wings. homologous structures, however, is an organ or bone with similar underlying anatomical features found in different animals; such as the arms of primates.
4. vestigial structures are structures that have no apparent function and appear to be residual parts from a past ancestor, such as wings of flightless birds.
5. Embryology supports the theory that organisms have a common ancestor in accordance to the theory of evolution.
Explanation:
Answer:
Deforestation is the major problem causing lack of rich species in Costa Rica. This is due to over grazing by cattle.This may lead to flooding which affect fertility of the soil.These animals graze on the plants without regulations,and cause erosion as their hoofs percolate the soil, further reducing soil fertility.
In addition to sustain the beef production, trees were fell to for cattle ranching.This ultimately contributed to loss of the forest species.
Banana plantation is an additional factor.Forest were cleared to cultivate banana, which affects forest population.
Explanation:
Homeostasis does continue when environments change.
Meiosis is the process by which sperm cells and egg cells are produced. In the male, meiosis takes place after puberty.
