True, major events like a super volcano's or asteroid strikes can send tons of ash dust and debris into the stratosphere and cause global cooling. <span />
The function of the plasma membrane is to only allow certain items through, while blocking the rest.
A gamete is randomly getting a copy of a chromosome from its mother and father. This means that gamete will get #1 from the mother and the next chromosome will be a pure chance of getting chromosome #2 from mother or father.
Explanation:
- Meiosis is the process that separates the two chromosomes and giving one copy of each to the gamete. This is the reason why egg and sperm together are forming zygote which is diploid.
- The main advantage of sexual reproduction is that each clone is different. Each and every egg is different from each other. This is the same in the case of sperm too.
- At the end of meiosis, males will have 1 cell with 4 sperms all are different in nature, but in females, it will one egg because, during cell division, one cell will hog the cytoplasm.
Answer:
b. 8P+ , 10no , 8e-
Explanation:
An isotope is a form of a chemical element whose atomic nucleus of an element contains a specific number of neutrons and protons. For example, the nucleus of a carbon atom contains 6 neutrons(no) and 6 protons(P+) and similarly in the nucleus of oxygen contains 8 neutrons and 8 protons . The number of neutron can varies in the nucleus of that element. Variation in neutrons form isotopes of the element. In nature, oxygen has three stable isotopes, ¹⁶O, ¹⁷O, and ¹⁸O, but ¹⁶O most abundant. The ¹⁸O isotope of oxygen contains 8 protons(P+), 8 electrons(e-) and 10 neutrons(no) instead of normal 8 neutrons.
Answer:
b. smoking can paralyze the ciliary escalator.
Explanation
Generally cilia in the respiratory tract of smoker will undergo paralysis for 1-3 hours after smoking, and generally paralyzed in chronic smokers.
This is because the toxins( the TAR) in the cigarette destroy the mucocilliary escalator that trapped inhaled pathogens in air as it passes through the bronchi and push them up with phlegm out of the respiratory tract.
Therefore ,with the loss of cilirary function, pathogens are retained in the lungs leading to respiratory tract infections