Normal cells stop growing (reproducing) when enough cells are present. For example, if cells are being produced to repair a cut in the skin, new cells are no longer produced when there are enough cells present to fill the hole (when the repair work is done).
In contrast, cancer cells don’t stop growing when there are enough cells present. This continued growth often results in a tumor (a cluster of cancer cells) being formed.
Causes of speciation
<span>Geographic isolation
In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.
</span>Reduction of gene flow
<span>However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random. Individuals in the far west would have zero chance of mating with individuals in the far eastern end of the range. So we have reduced gene flow, but not total isolation. This may or may not be sufficient to cause speciation. Speciation would probably also require different selective pressures at opposite ends of the range, which would alter gene frequencies in groups at different ends of the range so much that they would not be able to mate if they were reunited.</span>
Answer:
clam
Explanation:
puffer fish is the only omnivore present in this diagram. this shows clam is eaten by pufferfish. so the answer is clam
Answer: The atoms in a gas move at high speed.
The atoms in a gas spread in all directions.
A gas is a state of matter in, which atoms remains in a constant motion, they do not stick together. They are free and can move in all directions. The gas molecules expands to fill the available space. Hence, they can change shape and volume. The gas atoms being in a molecular state moves fast in high speed to break away from each other, to remain in a free state.
The cells directly responsible for cellular immunity are the cytotoxic T cells (lymphocytes).
Cellular immunity is an immune response against infectious diseases caused by viruses and some bacteria. This mechanism does not involve antibodies, but rather cytotoxic T-lymphocytes, phagocytes and the release of cytokines in response to an antigen. <span>Cytotoxic T cells, perform their function by killing infected cells via apoptosis.</span>