I found the missing part of this question.
Statisics on Human Population
<span><span>Year A.D. Number of People (in billions)
</span><span>1650 .50
</span><span>1750 .70
</span><span>1850 1.0
</span><span>1925 2.0
</span><span>1956 2.5
</span><span>1966 3.3
</span><span>1970 3.6
</span><span>1974 3.9
</span><span>1976 4.0
</span><span>1980 4.4
</span><span>1991 5.5
</span><span>2000 6.0
</span><span>2004 <span>6.4
</span></span></span>
The answer is it took 200 years more to double the population from 0.50 billion to 1.0 billion people. The year was 1850.
It was in 1925 when the population double again from 1.0 billion to 2.0 billion.
The correct answer is d: cDNA.
<span>cDNA or complementary DNA is DNA synthesized usually from messenger RNA (mRNA) by the enzyme reverse transcriptase. Because this molecule is from mRNA it contains only exons. cDNA is also produced naturally by retroviruses, for example, HIV virus.</span>
B. specific to a substrate
Answer;
-A teenager teaches her brother how to text (same generation).
Explanation;
-Cultural trait is a characteristic of human action that's acquired by people socially and transmitted via various modes of communication.Culture is the integrated pattern of human knowledge, belief and behavior. Every society has its own particular culture.
-Vertical transmission occurs from parents to offspring and is a function which shows that the probability that parents of specific types give rise to an offspring of their own or of another type. Horizontal transmission is cultural transmission taking place among peers in a given population.
