Answer:
In the semi-conservative method of DNA replication, each of the strands of the double helix acts as a template for replication.
Explanation:
Semi-conservative DNA Replication:
- Semi-conservative DNA replication produces two daughter helices from the original parent helix. One strand of the daughter helix is form the original template while the other is newly synthesized.
- This means that one strand will have the base sequence identical to the parent, while the other will be complementary to the template.
- This model was experimentally confirmed by an experiment conducted in 1958 by Meselson and Stahl. They used radioactive isotope of nitrogen i.e. N-14 or N-15. DNA molecules made with N-15 were allowed to replicate in the presence of N-14.
- After first replication, DNA molecules contained both N-15 and N-14 isotopes, disproving the conservative model that stated that the new helices are completely identical to the template.
- The second replication yielded only N-14 which disproved the dispersive model that the new helices are a combination of both the template and new strands.
<span>"Since the discovery of Galapagos in 1535, humans have brought many alien species to the islands—some intentionally, including goats, pigs, cats, and both ornamental and food plants (vegetables and fruits), to name a few—while others, including rodents, insects, and weedy plants, have been carried to the islands accidentally." </span>
Answer: d. alternation of multicellular generations
Explanation:
The gametophytic as well as the sporophytic generations are alternative in the life cycle of the multicellular plants. This can be seen among the land plants. This feature cannot be seen in the algal species as they are unicellular in nature. Thus cannot be seen in the relatives of charophyta algae.
It declines. Members above will die off due to starvation, and members immediately below will proliferate and kill off (through predation) the members below themselves.
