In bears, black fur is dominant over brown fur. A pure black bear is crossed with a brown bear and they have four cubs. Under ideal conditions, which of the following is true? All of the cubs would be black.
All of the cubs would be brown.
Half of the cubs would be black and half of the cubs would be brown.
One cub would be black and three cubs would be brown.
One cub would be brown and three cubs would be black.

All of the cubs would be black

We can use something called punnet squares

Let Pure Black Stand For BB and pure Brown stand bb

Let's set up our Punnet square

        bb    bb

BB    Bb    Bb

BB    Bb    Bb

Since Black is dominant over brown fur, the cubs should all be black.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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