A tall, heterozygous pea plant (Tt) is crossed with another tall, heterozygous pea plant. Use a Punnett square to determine the probability that the offspring is a short, homozygous pea plant (tt).(1 point) Responses 50% 50% 0% 0% 25% 25% 75%

Answer 1

To determine the probability of obtaining a short, homozygous pea plant (tt) from a cross between two tall, heterozygous pea plants (Tt), we can set up a Punnett square.

For a cross of Tt and Tt:

         T         t
      ----------------
   T |     TT     |   Tt   |
      ----------------
   t |     Tt     |   tt   |
      ---------------- 

The possible genotypes of the offspring from this cross are:

• TT (homozygous tall)
• Tt (heterozygous tall)
• Tt (heterozygous tall)
• tt (homozygous short)

Now let's count the genotypes:

• 1 TT
• 2 Tt
• 1 tt

From this, we can see that there is 1 tt out of 4 total genotypes.

To find the probability of the short homozygous offspring (tt):

\[ \text{Probability of } tt = \frac{\text{Number of } tt}{\text{Total number of offspring}} = \frac{1}{4} = 25% \]

So, the probability that the offspring is a short, homozygous pea plant (tt) is 25%.

Answer 2

Is a substitution mutation harmful to an organism?(1 point) Responses Yes, all mutations are harmful to organisms. Yes, all mutations are harmful to organisms. Substitution mutations are not a type of mutation. Substitution mutations are not a type of mutation. No, substitution mutations are never harmful because they are silent. No, substitution mutations are never harmful because they are silent. It depends on whether the resulting amino acid of the codon has changed. It depends on whether the resulting amino acid of the codon has changed.

Answer 3

The correct response is:

It depends on whether the resulting amino acid of the codon has changed.

Substitution mutations involve the replacement of one nucleotide with another in the DNA sequence. This can lead to different outcomes:

1. Silent mutations: If the substitution does not change the amino acid due to the redundancy of the genetic code, it is considered silent and usually has no effect on the organism.

2. Missense mutations: If the substitution changes one amino acid to another, it may impact the protein's function, potentially leading to harmful effects, beneficial effects, or no significant effect.

3. Nonsense mutations: If the substitution creates a stop codon, it can lead to a truncated protein, which often results in a nonfunctional protein and can be harmful.

Therefore, the impact of a substitution mutation is context-dependent, making the last option the most accurate.

Answer 4

Which statement best describes why Punnett squares are useful?(1 point) Responses Punnett squares are used to explain why incomplete dominance happens. Punnett squares are used to explain why incomplete dominance happens. Punnett squares are used to predict all possible allele combinations and their frequencies in parents. Punnett squares are used to predict all possible allele combinations and their frequencies in parents. Punnett squares are used to predict all possible allele combinations and their frequencies in offspring. Punnett squares are used to predict all possible allele combinations and their frequencies in offspring. Punnett squares are used to describe the phenotypes of organisms. Punnett squares are used to describe the phenotypes of organisms.

Answer 5

The statement that best describes why Punnett squares are useful is:

Punnett squares are used to predict all possible allele combinations and their frequencies in offspring.

Punnett squares are a tool in genetics that allow for the visualization of the potential combinations of alleles that offspring may inherit from their parents based on the parental genotypes. They show the probabilities of obtaining specific genotypes and, thereby, phenotypes in the offspring.

Answer 6

How are new viruses made?(1 point) Responses viral DNA or RNA copied in a host cell viral DNA or RNA copied in a host cell viral DNA or RNA copied in a virus viral DNA or RNA copied in a virus asexual reproduction asexual reproduction sexual reproduction

Answer 7

The correct response is:

viral DNA or RNA copied in a host cell.

Viruses replicate by entering a host cell and using the host's cellular machinery to copy their own viral DNA or RNA. This process produces new viral particles, which can then exit the host cell to infect other cells. Viruses do not reproduce in the traditional sense (asexual or sexual reproduction) because they rely on host cells for replication.

Answer 8

Which best describes a provirus?(1 point) Responses A provirus is bacterial DNA incorporated into viral DNA. A provirus is bacterial DNA incorporated into viral DNA. A provirus is newly replicated viral DNA after injection. A provirus is newly replicated viral DNA after injection. A provirus is the host cell’s DNA that has been destroyed. A provirus is the host cell’s DNA that has been destroyed. A provirus is viral DNA incorporated into the host cell’s DNA. A provirus is viral DNA incorporated into the host cell’s DNA.

Answer 9

The correct response is:

A provirus is viral DNA incorporated into the host cell’s DNA.

A provirus is a viral genome that has been integrated into the DNA of a host cell. This can happen during the lysogenic cycle of certain viruses, such as retroviruses. When a provirus is formed, it can remain dormant within the host's DNA and may be replicated along with the host's genetic material during cell division.

Answer 10

Why is it difficult to produce a vaccine for the common cold in humans?(1 point) Responses It has a viral genome that mutates very quickly. It has a viral genome that mutates very quickly. It is a spherical-shaped virus with many protein receptors. It is a spherical-shaped virus with many protein receptors. It is caused by retroviruses that insert viral RNA into the host cell's DNA. It is caused by retroviruses that insert viral RNA into the host cell's DNA. It attacks white blood cells that fight off foreign bodies.

Answer 11

The correct response is:

It has a viral genome that mutates very quickly.

The common cold is primarily caused by rhinoviruses, which are known for their high mutation rates. This rapid mutation makes it challenging to develop an effective vaccine, as the virus can quickly change its surface proteins, leading to variations that can evade the immune response generated by a vaccine. As a result, a vaccine that may be effective against one strain of the virus may not work against another strain that has emerged due to mutations.