This is when. The sequence of events that result in the contraction of an individual muscle fiber begins with a signal—the neurotransmitter, ACh—from the motor neuron innervating that fiber. The local membrane of the fiber will depolarize as positively charged sodium ions (Na+) enter, triggering an action potential that spreads to the rest of the membrane will depolarize, including the T-tubules. This triggers the release of calcium ions (Ca++) from storage in the sarcoplasmic reticulum (SR). The Ca++ then initiates contraction, which is sustained by ATP (Figure 1). As long as Ca++ ions remain in the sarcoplasm to bind to troponin, which keeps the actin-binding sites “unshielded,” and as long as ATP is available to drive the cross-bridge cycling and the pulling of actin strands by myosin, the muscle fiber will continue to shorten to an anatomical limit.
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:
decreased
Explanation:
10% rule: 10% energy gets passed on to the next trophic level, so there has to be less population to sustain them with the 10% energy given
Cholesterols are amphiphatic molecules. This property allow cholesterol to insert themselves into cell membranes by interacting with phospholipids which are also amphiphatic in nature. A molecule is said to be ampiphatic if it has both polar and non polar regions.
Answer:
The total blood given is 5.5 liters
Thus, total alcohol needed for BAC (blood alcohol content) to exceed 0.1 gram per 100 ml will be 0.1/100 × 5500 = 5.5 grams alcohol.
1 oz = 28.3 grams
28.3 gram water = 28.3 ml
It has 20 percent alcohol by volume,
Therefore, alcohol in one drink will be:
20/100 × 28.3
= 5.66 ml
= 5.66 × 0.79 (density of ethanol)
= 4.47 gram
Thus, no of drinks will be 5.5 g / 4.47 g = 1.2
Hence, 1.2 drinks will make the BAC to exceed 0.1 g / 100 ml in the blood.
