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pogonyaev
3 years ago
7

REALLY NEED HELP

Biology
1 answer:
Liono4ka [1.6K]3 years ago
4 0
T cell activation is initiated by an activated B cell.

The B cell presents antigens on its MHC receptors. The T cell recognizes the antigen bound to the MHC. There are other cosignals that fully activate the at cells but the antigen on the MHC receptor on the B cell is where it all starts.
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Plants that reproduce sexually and have flowers are called?
emmasim [6.3K]
The bryophytes, which include liverworts, hornworts and mosses, reproduce both sexually and vegetatively. The gametophyte is the most commonly known phase of the plant. All are small plants found growing in moist locations and like ferns, have motile sperm with flagella and need water to facilitate sexual reproduction.
6 0
4 years ago
Read 2 more answers
¿Qué se puede agregar a un átomo para hacer que un electrón sin valencia en el átomo se convierta temporalmente en un electrón d
NNADVOKAT [17]

Energía.

Explicación:

Generalmente, los electrones giran continuamente en las capas de los átomos. Si estos electrones se encuentran en las capas más externas de un átomo, se denominan electrones de valencia.

Son necesarios para las reacciones químicas de un átomo en particular con otro, a través de sus pérdidas o compartidas.

En los átomos sin valencia, sus capas más externas no tienen electrones en sus capas más externas, tales átomos son estables.

Sin embargo, si se suministra cierta cantidad de energía a dicho átomo, el electrón gana energía y, por lo tanto, se excita.

Por lo tanto, se mueven de niveles de energía más bajos a niveles de energía más altos, y hacen que el átomo sin valencia se convierta en valencia temporalmente, a medida que se mueven hacia la capa más externa.

Answer:

Energy.

Explanation:

Generally, electrons revolves continuously in the shells of  atoms.if these electrons are located in the outer most shells of an atom,they are refereed to as the Valence electrons.

They are needed for chemical reactions of a particular atom with another,through their loses or sharing.

In Non -valence atoms their outermost shells do not have electrons at their outermost shells,such atoms are stable.

However, if  certain quantity of energy is supplied  to  such atom, the electron  gains energy and therefore becomes excited.

They therefore move from lower energy levels to higher energy levels,and makes the non- valence atom becomes valence temporarily, as they move into the outermost shell.

5 0
3 years ago
Help me on this question; it’s about asexual reproduction
spayn [35]

Explanation:

organisms like amoeba, yeast, hydra and planaria, etc.

organism like hydra uses the method of budding for asexual reproduction , amoeba uses binary fission for a serial reproduction , planar uses regeneration and in the same way , plasmodium uses multiple fission

thankyou .

8 0
3 years ago
What is the function of the waxy, transparent top layer of leaves
Fantom [35]
It depend some plants have the waxy layer because of their cuticles and to make sure the leaf doesn't dry out or to protect it againts the harmful sun rays when directly shined on its good to have sun but not too much. HOPE THIS HELPS
5 0
4 years ago
A bacterium that you isolated from pond water appears to use light for energy. Based upon this information, you inoculate the or
FinnZ [79.3K]

The question is incomplete as it does not have the options which are:

  • there was no sulfur compound added to the medium, that could be used as an electron donor.
  • no oxygen was added to the medium so the organism died.
  • there is some inhibitory chemical that is preventing the growth of the bacterium.
  • you were using the wrong type of sunlight as the energy source for the bacterium.

Answer:

There was no sulfur compound added to the medium, that could be used as an electron donor.

Explanation:

In the given question, the bacteria which are found in the pond uses light energy to use carbon dioxide and form the glucose molecule. These bacteria are known as phototrophic bacteria.

The process of photosynthesis requires an electron donor and an electron acceptor to use molecule.

The organism when provided the light and carbon dioxide artificially in a culture, the bacteria were not able to grow. The reason for this could be accounted as that there was no electron donor found in the media like sulfur which could donate the electron during the chain reaction.

Thus, the selected option is correct.

4 0
3 years ago
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