One difference between mitochondria and chloroplasts is
a) mitochondria use nadh while chloroplasts make nadh.
b) mitochondria produce water from oxygen while chloroplasts produce oxygen from water.
c) mitochondria are only found in animal cells and chloroplasts are only found in plant cells.
d) the calvin cycle occurs in the mitochondria while the krebs cycle occurs in the chloroplast.

The right answer is B.

In the respiratory chain:

To reoxidize NADH, it is necessary to go through an electron transport chain: it is a series of proteins inserted into the inner membrane of the mitochondria.

These are aligned in energetic order, the first molecule has more energy than the last one.

The first in the chain picks up a pair of electrons (2e-) at each NADH (an H + proton is also given in the medium so that the NADH regenerate to NAD +) and transfers them to the adjacent molecule.

There are 5 sets of complexes involved in the respiratory chain. The first four (I, II, III and IV) are involved in the transport of electrons and the fifth (V) is involved in the synthesis of ATP.

As this transport progresses, the electrons "lose" their energy.

Finally, at the end of the chain, they are accepted by the oxygen (O2) which combines with protons of the medium to form water (2H + + 2e- + O2 -> H2O).

The energy "lost" by electrons and the presence of protons H + activate an enzyme, ATP synthase, also localized in the inner membrane. This enzyme catalyzes the production of ATP in large quantities.

There are 12 NADHs: 10 from the Krebs cycle and 2 from glycolysis.

In the photosynthesis:

In oxygen photosynthesis, water is the electron donor, whose dissociation releases oxygen while water is reformed from an oxygen atom of carbon dioxide:

2n CO2 + 4n H2O + photons → 2 (CH2O) n + 2n O2 + 2n H2O.

The equation is generally simplified by removing 2n H2O in both terms, giving:

2n CO2 + 2n H2O + photons → 2 (CH2O) n + 2n O2.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products