Answer:
B. A helicase enzyme unwinds the DNA molecule, then corresponding nucleotides are added to the separated original strand forming two separate semiconservative molecules
Explanation:
DNA Replication is an important phenomenon as far as cell division is concerned. It is the process whereby a DNA molecule doubles its content or forms two DNA molecules from one.
In the semi-conservative model of DNA replication, an enzyme called DNA helicase unwinds the double stranded DNA molecule into two single strands. The single strands are then used as template for DNA polymerase to synthesize another molecule of DNA. Hence, two separate DNA molecules comprising of one old strand and one new strand.
Answer: C. A natural disaster, such as a hurricane, struck the island.
A limiting factor is a resource or ecological condition because of which growth and distribution of an organism or group of organisms living in an ecosystem limits. A limiting factor can be of either physical or biological in nature. A limiting factor restricts organisms from occupying their fundamental niche. Examples of limiting factor are resources, stress due to overcrowding, disease or parasite and a natural disaster. According to the condition mentioned natural hazard can be the only limiting factor to limit the population at such considerable rate. Natural disaster is a physical limiting factor which has catastrophic impact of populations of different species living in an ecosystem. It has the potential to wipe out several inhabitants in one drastic event. Therefore, a natural disaster, such as a hurricane, struck the island can be a most likely explanation for the changes that the scientists observed.
Answer:
In an open system matter and energy can be transferred ·
In a closed system only energy can be exchanged ·
In an isolated system neither matter nor energy can be exchanged · The cell has to be an open system because it needs to exchange matter and energy and the only way to do so is through an open system ·
As an open system the cell allows nutrients to enter the cell and waste products to exit the cell ·
The cell does this through the use of a semi-permeable membrane
Explanation:
<span>Single events or several causes working together to produce extinction in a short period is referred to as mass extinction.
Example:
</span>Destruction of forests, mountains, and bodies of water to satisfy human needs result to the imbalance of nature which also give rise to global warming.
<span>Animals and plants have lost their habitats. They lost their means to live. They lost their food sources and they suffer and die because of humans irresponsible acts.</span>
