How are gross production and net production different?
a. net production is always greater than gross production.
b. net production is always less than gross production.
c. only animals have net production.
d. only plants have net production.

The correct answer is B) Net production is always less than gross production.

Gross production or gross primary productivity ( GPP) is the total amount of energy produced by producers in a particular area and a particular time.

GPP= rate at which organic matter is produced + rate of  respiration

Net production or net primary productivity ( NPP) is the net amount of energy that is stored by producers in unit area and time. It does not include the energy lost in respiration.

NPP= GPP- rate of respiration

Thus, net production is always less than gross production.                  

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.