Answer:
The probability of their first child being colourblind is 1/4
Explanation:
Red-green color blindness is an X-linked recessive disorder.
A woman with normal vision whose father was colorblind has children with a man with normal color vision.
In an X-linked condition, the males only need to get one copy of the affected allele to have the condition and this copy is also inherited by a female offspring.
So in this case, the woman receives the affected recessive allele copy from her dad but since she still has normal vision, she received the normal copy from her mom so she is heterozygote for the trait.
The woman with normal color (XRXr) has a father who is color blind (XrY) has children with a normal man (XRY)
The cross would be
XRXr x XRY
XR Xr
XR XRXR XRXr
Y XRY XrY
Probably of having an affected child is 1/4. Thus, the probability of their first child being colourblind is 1/4
The answer is step 3. Nerve impulse on a muscle cell induces release of calcium ions
Steps of a muscle contraction are:
1. Nerve impulse travels down the axon and causes a release of acetylcholine.
2. Acetylcholine binds to the receptor of a muscle cell.
3. Nerve impulse on a muscle cell induces a release of calcium ions.
4. Calcium ions induce exposing of myosin to actin.
5. Sliding of actin filaments past myosin filaments.
6. The muscle contract.
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of science is to move "form taxa" to biological taxa whose affinity is known.
