Answer: B. The release of calcium ions causes myosin and actin to attach to each other. This statement best describes a cause and it's effects that occur during the process of muscle contraction.
Muscle contraction can be explained by sliding filament theory.
1. Activation of muscles: the motor nerve generates an impulse to transfer signals from neurons to neuromuscular junction. This stimulates sarcoplasmic reticulum to release calcium into the muscle cells.
2.Contraction of muscles: calcium in the muscle cells binds with troponin causes actin and myosin to bind. Actin and myosin in the muscle binds and contract by utilizing ATP as a source of energy.
<span>Notice a couple of things
different between (A) and (B). It was NOT the first time a biologist
proposed that species changed through time (so it's not B). But it
finally *solidified* that idea by giving "change through time"
(evolution) a MECHANISM. It gave a plausible explanation for WHY
species change over time, in a testable way that made sense and had
evidence to support it.
So it finally dismissed the idea that species are constant.
It also emphasized that the simple presence of *variation* within a population was a key reason for evolution.
While we're at it ... (C) is wrong because it's not *individuals* that
acclimate (adapt) to their environment, but the population (the species)
as a whole.
And (D) is wrong because it had nothing to do with economics or the monarchy.</span>
Answer:
all living things have cells with a nucleus
C. The question is hinting at the similarities between how single cellular organisms maintain homeostasis by regulating water levels the same way the kidney does for multi cellular humans.
