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Andrew [12]
3 years ago
5

In 1939, the use of DDT (a powerful synthetic chemical) as an insecticide was discovered. The United States adopted its widespre

ad use, producing up to 100 million kilograms per year (200 million pounds per year). Twenty years later, severe side effects started to be reported as a result of DDT use. Which was an advantage of using DDT?
insect and pest populations decreased

birth defect rates increased

cancer rates increased

fertility rates decreased
Biology
2 answers:
olganol [36]3 years ago
7 0
The answer is <span>insect and pest populations decreased.
</span>

DDT (dichlorodiphenyltrichloroethane) was used as an insecticide which is a substance used to kill insects. That resulted in decrease in insect and pest populations. It is a persistent and non-degradable insecticide, but as well organic pollutant readily accumulated to soils and consequently affects organisms.
nordsb [41]3 years ago
7 0

Answer:

A. insect and pest populations decreased

Explanation:

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A recessive allele causes phenylketonuria (PKU) when homozygote. If the frequency of the recessive allele is 0.05 in the populat
Radda [10]

Answer:

0.095

Explanation:

Phenylkentonuria is a disease caused by a recessive allele.

The frequency of the recessive allele + the frequency of the dominant allele equals 1.

The frequency of the recessive allele is q = 0.05

The frequency of the dominant allele then is p = 1  - q = 0.95

If people mate randomly, the frequency of the homozygous dominant genotype will be p², the frequency of the heterozygous genotype will be 2pq and the frequency of the homozygous recessive genotype will be q² .

2pq=2× 0.05 × 0.95

2pq=0.095

The heterozygote frequency in the population is 0.095

4 0
3 years ago
In a certain plant, tall stems (t) are dominant to short stems (t). a farmer crosses a short-stemmed plant with a heterozygous l
melisa1 [442]

The answers would be:

Genotype                Phenotype

     Tt                      Tall stemmed

     tt                       Short stemmed

Genotypic ratio : 2:2 or 1:1

Phenotypic ratio: 2:2  or 1:1  

<u />

<u>You can read on to see how this was done:</u>

Tall stems (T) are dominant to short stems (t).

First figure out the genotypes of the parents. We have a short-stemmed plant and a heterozygous long-stemmed plant cross.

For short stem to occur, you need 2 pairs of short alleles. So the first parent would have a genotype of tt.

Heterozygous long-stemmed means that the parent has one of each allele. So the genotype of the second parent would be, Tt.

Now we can make our Punnett Square.

tt x Tt

<u>       t        t  </u>

<u>T |  Tt  |   Tt</u>

<u>t  |   tt  |   tt</u>

Let's list down the genotypes and phenotypic results.

Genotype        no.         Phenotype

     Tt                 2           Tall stemmed

     tt                  2           Short stemmed

So from that we can answer the other questions:

Genotypic ratio : 2:2 or 1:1

Phenotypic ratio: 2:2  or 1:1  

8 0
3 years ago
Why the answer is B???
mars1129 [50]
The answer is b because that's the only place where the leaf can be water to go through transpiration and the water cycle
5 0
3 years ago
Why is the lower epidermis of zebrina a complex tissue
NemiM [27]
This is just an educated guess. As the purple pigment, caused by anthocyanins, are on the bottom side of the plant, their purpose could probably be to direct the light. Specifically, a purple pigment on the bottom of the plant would absorb certain wavelengths near the purple spectrum, and reflect other wavelengths back toward the portion of the plant with chlorophyll. In this way, light does not simply pass through the leaf, instead it is reflected back in towards the chlorophyll to maximize the amount of light being used for photosynthesis.
3 0
3 years ago
For what type of study does the United States Census Bureau assist scientists by completing research?
mariarad [96]
A)Demographic; because the census studies things such as births,death, and even disease which show changes in human population
5 0
3 years ago
Read 2 more answers
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