The chemical synapse is bounded by the neuron, from which neurotransmitters are released across the synaptic cleft, to the neuron, where the receptors for that neurotransmitter are located.

The chemical synapse is bounded by the presynaptic neuron,from which neurotransmitters are released across the synaptic cleft, to the postsynaptic neuron where the receptors for that neurotransmitters are located.

Explanation:

Synapse is the junction between two neurons.

Typically a synapse involves junction between an axon terminal of one neuron  called presynaptic neuron .and dendrites of a second neuron , known as post synaptic neuron.

Synapses can be of two types: A chemical synapse and an electrical synapse.

Electrical synapse involves , action potential  conducts directly between adjacent cells through structures called gap junctions.

A chemical synapse involves chemicals called neurotransmitters for the transmission of action potential.

because the light is a great source of energy for the plants to survive. (i hope this )

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.