The correct answer is that "the T cell enters a state of anergy".
The activation of T cells requires two signals: (1) antigen specific signal presented by an antigen presenting cell (either a macrophage or a dendritic cell) that activates t cell receptors and (2) co-stimulatory signals that is not antigen specific but rather found in the plasma membrane of the antigen presenting cell (i.e. CD28). In the absence of a co-stimulatory signal, the t cell will enter a state of anergy or the inability to produce an immune response toward an offending antigen.
Answer:
Since the nature of pollutants is not mentioned in the question, several speculations can be made here.
- Pollutants can affect the photosynthesis: Some pollutants are toxic to plant metabolic reactions such as photosynthesis. This is because of their oxidative nature that can damage the photosystems. This ultimately impairs the plant functioning, e.g. ozone in the air.
- Pollutants can affect the plant-associated microbial communities: Some pollutants such as antibiotics can target plant-associated bacterial communities that are required for plant health. Just like the human gut, plants also have beneficial bacteria that live inside the plant tissues. These bacteria are called endophytes. The harmful nature of the compounds can affect those bacteria which decreases plant fitness.
- Pollutants can compete with nutrients that act as limiting factors: Some pollutants are hydrophobic in nature and make the beneficial nutrients less available to the plants. Likewise, some pollutants reduce the bioavailability of plant necessary nutrients directly. This results in reduced growth and development in plants.
- Pollutants can cause physical damages to plant tissues: Some pollutants are highly reactive in nature and can cause physical damages to the plants. This will result in the attack of pathogens at the wound site which can later take control of host metabolic machinery at later stages. Resultantly, plant fitness is decreased and in some cases, it dies off completely.
It is important to consider that some pollutants are taken up easily by plants whereas other pollutants are difficult. This is because of their water solubility criteria. If a pollutant can be taken up by plant directly, it can cause more damages to the plant as compared to the pollutant which interacts from outside.
Alleles are letters that represent dominant and recessive traits.
A capital letter represents a dominant trait
A lowercase letter represents a recessive trait.
Dominant traits over shadow the recessive ones. This is known as complete dominance.
Referring to your questions let's us the alleles HH, Hh, and hh for the height of the pea plants.
But what do those letters mean?
HH = homozygous dominant (Tall)
Homo means same.
hh = homozygous recessive (Short)
Now this is different: here's Hh.
There's a capital AND lowercase letter.
This means that the plant carries the gene for tall and short plants, and can pass on either trait to the offspring.
BUT the dominant always over shadows the recessive. So Hh is a tall plant.
Hh = heterozygous (hybrid) (Tall)
You can interpret hetero meaning different.
Now I hope you're with me!
For question two it asks if a short plant can ever be a hybrid.
Referring to what I just said, that answer would be no.
Because there is no dominant trait to over shadow the recessive.
And short plants have the hh alleles, and they are homozygous NOT heterozygous (hybrid).
I hope this helps, and makes sense! If you have any questions please let me know. Genetics can be confusing.
