In a certain plant, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed.
Which of the following is the expected proportion of phenotypes in the next generation?
3 red, 1 white.
2 red, 2 white.
4 red, 4 white.
1 red, 3 white.
The Correct Answer is B
In this cross, the plant heterozygous for red flowers has the genotype Rr (where R represents the dominant red allele and r represents the recessive white allele), while the plant with white flowers has the genotype rr.
The possible offspring from this cross would have the genotypes Rr (red), Rr (red), rr (white), and rr (white), resulting in a 1:1 ratio of red to white flowers.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV.
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
Correct Answer is B
Explanation
The atomic number of an element represents the number of protons in the nucleus of an atom of that element.
Since lithium has an atomic number of 3, it has 3 protons in its nucleus.
Choice A is not correct because 7 is the mass number of lithium, not the number of protons.
Choice C is not correct because 12 is not the atomic number or mass number of lithium.
Choice D is not correct because 4 is not the atomic number or mass number of lithium.
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