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nika2105 [10]
2 years ago
15

Once you have been exposed to an antigen, you develop immunity against the same antigen because

Biology
1 answer:
Paha777 [63]2 years ago
3 0
Because an antibody is "made" relative to the antigen, but kept at low levels when you are exposed the first time ("primary immune response"). The second time you're exposed to the same antigen, memory cells recognize it and the body produces a high level of antibodies, and the level of antibodies usually remains higher for a longer time ("secondary immune response"). This is your basic immune response (primary and secondary).

This explains exactly why vaccines are effective to extremely effective.
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50 POINTS <3
melisa1 [442]

Independent Variable: Scenarios (such as different times of the day or places) used to check if a person will become depressed or not.

Dependent Variable: Number of people diagnosed with depression.

Constant: Amount of people who do not understand depression.

Control: How your setting can impact mood and performance.

3 0
3 years ago
Which planet has a greater mass than the combined mass of all the remaining planets and their moons?
faltersainse [42]
Id say Jupiter cuz its huge. it's the largest planet in our solar system.
5 0
3 years ago
Read 2 more answers
The major difference between angiosperms and gymnosperms comes from the _____.
kumpel [21]

Answer:

presence or absence of a protective covering over the ovule

Explanation:

In angiosperms, seeds develop from ovules and are enclosed in the ovary. So, their is the presence of protective covering making the seeds enclosed.

On the other hand, gymnosperms have seeds that are borne on cones, so they are naked due to the absence of any protective covering over the ovule.

4 0
3 years ago
Which of these sentences characterizes the regulatory mechanisms of gene expressions in organisms?
scZoUnD [109]
<span>According to a source the answer is B. They save energy and metabolites and help the organisms to respond to the environmental changes.

</span>A genotype is a set of genes in the human DNA responsible for different traits. It represents your complete identity that you will inherit from your parents and ancestors.
<span>On the other hand, a phenotype is how that trait expresses physically, a characteristic, a visible description of your physical features, including height, eye color, overall health, history of diseases, the ability to gain or lose weight fast, what type of food you like, what you enjoy and what you hate. </span>
5 0
3 years ago
Hemlocks are a common type of tree in the northern forests of the United States. In studying one forest, a forester noticed that
Vlada [557]

Answer:

b. making an observation and asking a question

Explanation:

In scientific method there need to be a situation to be study. In this description, the scientist first observed that in a certain region there is some kind of trees and the other variable is the great amount of deer.

After making different observations, and some research of other areas similar to the one that is study, she is asking what is the relation among the animals and the trees.

The next step will be to formulate a hypothesis using all the data and the two variables that she observed.

8 0
3 years ago
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