There are choices for this question namely:
<span>A) B cells produce IgE antibodies
B) B cells release cytokines
C) cytotoxic T cells present the class II MHC molecule-antigen complex on their surface
D) helper T cells release cytokines
The correct answer is "helper T cells release cytokines". Cytokines are released by helper T cells when B cells attach to them via receptors. These T cells "help" these B cells to differentiate by secreting certain cytokines. When B cells differentiate, they are converted to plasma cells and able to secrete antibodies to the antigen presented to the T cells. </span>
Mitochondria are unusual organelles. They act as the power plants of the cell, are surrounded by two membranes, and have their own genome. They also divide independently of the cell in which they reside, meaning mitochondrial replication is not coupled to cell division. Some of these features are holdovers from the ancient ancestors of mitochondria, which were likely free-living prokaryotes.
<u>Answer</u>:- Active transport
<u>Explanation</u>:-
There are two types of membrane transports
1. Passive transport - this type of transport occurs without the input of any energy and the molecules move along the concentration gradients that is from <em>high concetration to low concentration.</em>
2. Active transport- this type of transport takes place to move the molecules against the concentration gradient that is from <em>low concentration to high concentration.</em>
<em>The active transport is of two types:</em>
1. <em>Primary active transport-</em> in this type of transport <em>ATP</em> is used as an energy source to move the substances against the concentration gradient.
2.<em>Secondary active transport</em> - in this type of transport the gradient formed by the active transport is utilized and it involves the movement of 2 substances at a time aross the membrane. That is the movement of one molecule is coupled to another.
- The membrane proteins that are associated with active transport are called as <em>carrier proteins</em>. These proteins have a binding site for the molecules that they transport. Once they bind to the specific molecules, a conformation change is induced and this leads to the transport of the molecule across the membrane.
So, the <em>active transport is basically responsible for utilizing the energy from ATP and carrier proteins to move the substances across the membrane against their concentration gradient i.e. from low concentration to high concentration.</em>
Fertilization and formation of the zygote occur Within the body of mosquito.
Zygote, from the Ancient Greek (zygtós), "attached, yoked," from (zygoun), "to join, to yoke," A fertilization between two gametes produces a eukaryotic cell. The genome of a zygote, which consists of the DNA from each gamete, is what makes up a new individual creature and holds all of its genetic material.
The zygote is the first developmental stage in animals with many cells. When an egg cell and sperm cell unite to produce a new, distinct organism, a zygote is created in humans and the majority of other anisogamous species. With the aid of mitosis, the zygote can divide asexually in single-celled organisms to create identical progeny. The chloroplast DNA (cpDNA) of a Chlamydomonas zygote is inherited uniparentally from the parent with the mt+ mating type; as a result, such cells are typically uncommon. The mapping of chloroplast genetics through recombination was made possible by these uncommon biparental zygotes.
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There are different kinds of tides. This change occur because when the gravitational pull of the sun works along with the gravitational pull of the moon on Earth, it leads to the oceans bulging out.
- This result above makes the high tides as been little higher and low tides been little lower than normal.
Spring tides are known to be the deepest as oceans levels are highest in this kind of tide. The neap tides are known to be the shallowest.
This often occurs when the moon, earth, and sun are said to be at a right-angled plane. Therefore, the gravitation pull of the moon and sun on the oceans do counteract each other making its net effect is smaller.
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