The pig heart is big,and the chicken heart is small.
Answer:
The correct answer is B.
Explanation:
Option A is wrong. Mammals were not the prominent species before the extinction of dinosaurs because the mammal species that lived during the dinosaurs' era were so small that they only weighed several grams and occupied small areas as their habitats.
Option C is wrong. As dinosaurs became extinct, reptiles and "birds" remained as their descendant which evolved to some of the species that we know today.
Option D is wrong. Pangea started to break up to form the geographic isolation for the diversion of many species around 175 million years ago.
So the correct answer is B. Massive extinction disrupts and changes the food chain in such a big way that it triggers a domino effect that leads to species adapting to their new environment and diversifying thus forming new species in the process.
I hope this answer helps.
No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive.
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
Learn more about Sickle-cell anemia on
brainly.com/question/14505007
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Famine- High population means more mouths to feed
Disease- Diseases usually spread more quickly with people who live closer( as it can just move from one person to the other)
War- People like to fight for land, resources, money, etc. And having more of those things mean they are more able to support families, communities, and more.
(Hope this helps a little)
Answer: A
Explanation: the ice age posed a new chalenge to deer mice and on the ice the preadators could spot the darker deer mice better than the light deer mice.
