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:
The correct answer would be the pulmonary vein and the superior vena cava.
Pulmonary vein is a blood vessel of pulmonary circulation which carries oxygenated blood from lungs to the left atrium of the heart. Hence, it is rich in oxygen and carries carbon dioxide in the least amount.
In contrast, vena cava is a part of systemic circulation and carries deoxygenated blood from the body to the right atrium of the heart. They are two venae cavae in human beings namely; inferior vena cava (carries blood from lower body) and superior vena cava (carries blood from head, arms and upper body). Hence, it contains maximum carbon dioxide and least oxygen.
They are important in long term memory because they respond faster in a second infection with the same pathogen
D:
a,b,c are inherently bad or simply not helpful