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A. Which determines the other—phenotype or genotype? Explain.
The genotype, the genetic makeup of an organism, determines the phenotype, what the organism looks
like. This is because the genes determine the proteins that are made by the organism.
B. In pea plants, the gene for purple “P” flowers is dominant over the gene for white “p” flowers?
What is the genotype of a heterozygous purple-flowered pea plant?
Pp
What is the genotype of a white-flowered pea plant? pp
C. How is the product of meiosis different from that of mitosis? Meiosis produces 4 sex cells which
have 1/2 the number (haploid) of chromosomes as compared to mitosis which makes 2 body
cells with the diploid number of chromosomes that are identical to the parent cell.
D. A squirrel normally has 40 PAIRS of chromosomes in its cells.
After MITOSIS occurs, how many pairs of chromosomes would be in the squirrel’s body cells? 40
After MEIOSIS occurs, how many pairs of chromosomes would be in the squirrel’s sex cells? No pairs;
40 individual chromosomes
E. Respond to this: “Because the offspring develops inside the female, it will be more like her.”
Each parent gives 1/2 of the genetic material to the offspring. This is what determines what the
offspring is like, not where the offspring develops.
F. During Inquiry 19, some offspring displayed more traits of their fathers and some displayed
more of their mothers. If each parent donates one gene for each trait, how can this happen?
The offspring will look most like the parent that gives the most DOMINANT genes.
G. Hanging earlobes (H) are dominant over attached earlobes (h). Complete a Punnett square
showing the possible offspring from an Hh male and an hh female. Then answer the questions.
- What are the chances of these parents having an offspring with hanging earlobes? 2/4 or 50%
With 4 offspring, will 2 definitely have hanging earlobes and 2 attached earlobes? Explain. NO, each
offspring will have a 50% chance of having hanging earlobes.
-If an offspring has attached earlobes, can we assume its genotype is hh? Explain. Yes, since attached
earlobes are recessive, offspring have to get the recessive gene from both parents to show the trait.
-If an offspring has hanging earlobes, can we assume its genotype is Hh? Explain. No, since this trait is
dominant, the genotype might be HH or Hh and still show the trait. Just 1 copy of the dominant gene is
required.
H. Occasionally a trait not observed in either parent appears in an offspring. How this can happen?
Heterozygous parents may each give a recessive allele (gene) so the recessive trait will “reappear”.
I. Which parent actually determines the sex of an offspring? Explain. DAD - Each parent gives a
sex chromosome, X or Y. Females have XX and males have XY. Females can only give a X
chromosome. If the dad gives an X the baby is a girl. If dad gives a Y the baby is a boy.