If parents wanted to learn more about their genetic history and the possibility of passing a genetic disease on to a child, they should

have a carrier identification test
be tested for pku
see a genetic counselor
have a carrier identification test, and see a genetic counselor

The correct answer is the last option.

Explanation:

Carrier identification test is a screening test that tells if a person is carrier of a particular autosomal recessive disease. It helps in determining the possibility of passing that disease to a child.

Genetic counsellor is professional who is expert in human genetics, research, lab work, counselling, et cetera. After the test, it is best to contact a genetic counsellor as he can explain the family pedigree of the disease. He can best explain the probability of passing a genetic disease to the child.

These are the events occurring at synapse for the transmission of nerve impulse across the synapse from one neuron to another. The order of events is as follows: 4 - 1 - 5 - 3 - 2.

Explanation:

The correct order of events during the transmission of nerve impulse from one neuron to another is as follows:

4) Action potential reaches axon terminal of presynaptic neuron.

1)  Ca2+ enters axon terminal.

5) Neurotransmitter released by exocytosis.

3) Neurotransmitter binds to postsynaptic receptor.

2) Ligand-gated ion channels open in postsynaptic membrane.

- The transmission across the synapse can be either electrical or chemical. Here is this case we are talking about chemical transmission.

- When the action potential reaches the axon terminal, the voltage gated calcium channels open and there is influx of calcium from the synapse.

- This causes the fusion of synaptic vesicles with the membrane and exocytosis of neurotransmitter.

- These neurotransmitters bind to the receptors on post synaptic membrane and cause opening or closing of voltage gated channels.