I think maybe the nephrons ...but not sure...
Traits are determined by genes
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A theory that states that only the organism with traits that are useful to the environment survive. For example, short-neck giraffes would’ve died out years ago as they can’t reach the trees nor eat grass on the ground.
Answer:
It occurs in organisms because an organism with a beneficial trait/mutation have a higher chnace of surviving compared to organisms that do not. So the organsims that do survive pass on their genes to the next generation, and the bext generation will pass on those genes to the generation after and so on. But all the organisms that do not possess a beneficial trait/mutations will not survive, therefore they cannot reproduce and pass on those genes to their offspring. This means that most of the population will posses that trait/mutation.
Example: Spotted moths camouflage with bark so they are seen by predators and eaten. Black moths are easily seen by predators and are eaten. Spotted moths then pass on their genes to the next generation of moths.
Answer: A. A blockage in the aorta
Explanation:
A heart attack happens when one or more aorta or coronary arteries get blocked. With the passage of time, the coronary artery becomes narrow that is because of the deposition of various substances such as fat, cholesterol and other reserves. This restricts the smooth circulation of blood hence results in heart attack or heart stroke.