I think it’s a, hopefully you get it right!
Answer:
The preferable option will be - A.
A. similar environments and specific traits increased their chances of survival.
Explanation:
- The shark and dolphins have similar body shape and fins. But shark is a fish and dolphin is a mammal.
- Both of them are exposed to similar kind of environments. Both of them possess a specific kind of alternative characters and traits.
- So, Some species may have similar body structures even if they are not related because they evolved in similar environments and specific traits increased their chances of survival.
Answer:
D. Selection has led to decreases in the size of fish at the age of reproductive maturity.
Explanation:
The larger body size of the fishes is not an adaptive trait as it reduces the survival chances of these fishes. The process of natural selection tends to increase the frequency of the traits that increase the survival fitness of the organisms. Here, the fishes with smaller body size at the reproductive age have greater chances of survival and would reproduce more to leave more progeny. Over the generations, the selection pressure would increase the proportion of fishes that are smaller during reproductive age.
Positive: You get to see different animals, see all kinds of habitats, learn new facts about all the animals and see them maybe in action!
Negative: They might be sleeping, In a cage or fence so they can't get out, restricted.
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
