Research suggests that learning may involve:
1. ca²⁺ influx into a postsynaptic cell, causing biochemical changes and enhanced response to stimulation.
2. strengthening the sodium-potassium pump.
3. changes in action potential duration caused by blocking voltage-gated k⁺ channels.
4. synaptic changes caused by decreasing the size of the synaptic cleft and increasing the effectiveness of neurotransmitter diffusion.
5. synaptic changes causing slower reuptake of neurotransmitter from the synaptic cleft.

Suppose a particular species of tulip plant has three alleles for the gene that codes for flower color. the cr allele produces red tulips, the cp allele produces purple tulips, and the cw allele produces white tulips. cr is dominant over cp and cw, and cp is dominant over cw. for each of the following crosses, determine the expected ratio of offspring for each flower color. cr cp x cp cw cr cw x cp cw 1 red: 1 purple : 0 white, 1 red: 2 purple: 1 white, 2 red: 1 purple 1 white, 1 red: 3 purple : 0 white, 2 red: 0 purple : 2 white, 2 red: 2 purple : 0 white