T cell receptor, Cytotoxic T Cell, CD4, Antigen, Bacterium,
B – cell, Cell mediated response, Class II MHC, Cytokines, and Humoral Response
are the components for the activation of a helper t cell by a dendritic cell.
Answer:
D. There is no enough oxygen in the culture fluid
Explanation:
The cells in the test tube need to carryout one of the important metabolic processes of living organisms - respiration. The process involves the breakdown of glucose to generate energy for other metabolic processes in the cell.
Respiration can be carried out in the presence of oxygen (aerobic) or in the absence of oxygen (anaerobic). Human cells are primarily aerobic but can carryout respiration anaerobically in the presence of inadequate oxygen.
For aerobic respiration, glucose is broken down in the presence of oxygen to produce carbon-dioxide, water and energy in the form of ATP:

<em>In the absence of oxygen, the glucose becomes converted to lactic acid and a smaller amount of ATP is produced as compared to aerobic respiration.</em>
<em>Hence, lactic acid gradually builds up in the absence of oxygen due to anaerobic respiration.</em>
The correct option is D.
<u>Answer:</u>
<em>It is the biosphere and hydrosphere that interact when a drought causes a wildfire that destroys a forest.
</em>
<u>Explanation:</u>
Hydrosphere consists of all the water bodies of earth like oceans, seas, rivers, lakes etc. a drought occurs due to scarcity of water which affects the hydrosphere. The scarcity of water causes plants and trees to dry up and become more prone to catching fire
Biosphere includes all the living organisms of the earth. It includes plants, trees, birds, insects, animals etc. A drought dries up a whole area and a small fire that starts up somewhere in a forest would then engulf the whole forest.
<h3>
(^_^)/~~</h3>
Question:
Which subatomic particles are most important in the transfer of energy in living organisms?
Answer:
Electrons.
Extra Information:
An electron is an elementary particle having a charge of -1. It orbits the nucleus of atoms in shells (I.e., the K, L, M, N, O, P, etc.)
Answer: a-Male cones are smaller than female cones.
The cones are the characteristics of the gymnosperms plant species specifically to the Conifers. These plants exhibit naked ovules and the pollination in these cones is aided by the wind pollination. The male cones are smaller than the female cones and grows on the lower branches of the trees whereas the female cones grows on the higher branches. Each bract or scale of the male cone exhibit numerous pollen grains which are blown away by the wind and they pollinate the ovules of the female cones. Each bract or scale of female cone exhibit an ovule at the lower end. Each ovule is fertilized by the pollen to form the seed.