1) Photosynthesis uses sunlight energy to produce
sugar. Sugar goes from one cell to another until it reaches the cells which don’t
have access to sunlight (or they don’t get enough sunlight), so they can’t make
any photosyntesis or they make very little photosyntesis. That’s how the leaves
of a plant feed the roots of the same plant. When that cell receives the sugar,
it makes cell respiration to convert it back to water and CO2 and release energy.
When an animal eats a plant, animal cells also make this respiration process
with the sugar.
The chemical equation is basically the opposite:
Photosyntesis: water + CO2 -> O2 + sugar
Respiration: sugar + O2 -> CO2 + water
2) The DNA duplication is semiconservative, which means each
new double chain contains 1 original molecule and 1 newly synthesized molecule.
When DNA is duplicated, each one of the molecules (chains) acts
as a template for one of the chains that are being synthesized. Wherever there
is an A in the old molecule, the new molecule will have a T. G goes with C, C
goes with G and T goes with A. The way this happens is related to the number of
hydrogen bonds (C and G have 3, whereas A and T have 2) and the molecular size
(A and G have 2 cycles, whereas T and C have 1 cycle – so it is always a big
one with a small one, total = 3 cycles). You can compare it with a chocolate mold:
if you want a chocolate to be heart-shaped, you have to get a mold which has a
heart-shaped hole and put the warm chocolate inside. So the mold and the
chocolate have the opposite shape – complementary shape. But in this case, once
the duplication process ends, mold and new DNA stay together as a brand new
couple, and the mold never goes back with the other mold.
Answer: Booster dose of vaccine is given to elicit a secondary immune response ( by means of re-exposure of pathogen in the booster dose) so that more number of long lived antibody producing plasma cells are produced in the body.
Due to this, a higher level of protection is created in the body.
Whenever the body encounters the disease causing agent, it can easily clear off the infection.
Thus, booster dose serves as an additional vaccine dose to boost the memory of the immune system against a particular disease.
Example of vaccine that require booster dose- HPV ( human pappiloma virus), Hepatits A, Hepatitis B, Polio.
Answer:
A community includes both Biotic and Abiotic components of the environment.
Explanation:
Answer:
According to Dr. Ray Schiling (member of the American Academy of Anti-aging medicine) about 1.5 million people suffer from peanut allergies. The seeds of peanut (<em>Arachis hypogea</em>) contain an array of allergens that can induce the production of IgE specific antibodies predisposed individuals. Ara1 and Ara2 are most common seed storage protein that cause allergy. Other allergen proteins such as Ara3 to Ara 17 have also been identified that cause allergy.
Entry of peanut allergen into body
When peanut allergens enter the body of an individuals it leads to development of different symptoms like itchy skin, tingling sensation, nausea, runny nose and anaphylaxis.
Allergic response
There are two subsets of T-cells Th1 and Th2. Both invoke different response to allergens. Th1 direct a non-allergic response while Th2 direct allergic response ranging from releasing of histamine to anaphylactic response. The presence of IL-12 cytokines direct a Th1 based, nonspecific response.
Mechanism of allergic response (interaction between helper T cell and B cell)
Step 1.
When allergen enter to body they are encountered by B cells. Immunoglobulin receptors on the surface of B cells recognize antigen (Peanut allergens) and get attached, which are then internalized and processed. Within B cells the fragments of antigens combine with HLA class 2 proteins.
Step 2
HLA class 2 with antigen fragments (peanut allergens) then display on the surface of B cells.
Step 3
Receptors on the surface of helper T cells recognizes the complex of HLA class 2 and antigen fragments (peanut allergen) and is activated to produce cytokines, which activate the B cells.
Step 4
B cell is activated by cytokines and begins clonal expansion. Some of the progeny become anti-body producing plasma cells while other become memory B cells.
Most sand dunes are created by deposition by Wind.
