Punnett squares are used by geneticists to determine the probability of different offspring genotypes. In the one shown below, what letter(s) belong in the lower right box?
A. AA
B. Aa
C. aA
D. aa
From the given Punnett square, we can cross the genotypes of the two parents and established the phenotypes the offspring will have. The Punnett square is filled as:
|
|
A |
a |
|
a |
Aa |
aa |
|
a |
Aa |
aa |
The requested answer is aa.
Therefore, the Correct Answer is D.
More Questions on TEAS 7 Science
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Q #1: Which of the following best describes veins?
A. thick walled, small lumens, low pressure, lack valves
B. thin walled, large lumens, low pressure, have valves
C. thin walled, small lumens, high pressure, have valves
D. thick walled, large lumens, high pressure, lack valves
Answer Explanation
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Q #2: Pathogens Which of the following microorganisms lack their own metabolic pathways and can only reproduce inside of a host cell?
A. Bacteria
B. Viruses
C. Helminths
D. Protozoa
Answer Explanation
The disease-causing microorganisms are known as pathogens, which include bacteria, fungi, protozoa, worms, viruses and prions. These organisms have distinguishing cell structures from each other. The most notable difference between viruses and other pathogens is that viruses lack a metabolism mechanism of their own and ability to produce proteins encoded by their DNA or RNA. However, they viruses rely on machinery of the host cell to produce their proteins and replicate their genomes.
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Q #3: 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?
A. 3 red, 1 white
B. 1 white, 3 red
C. 2 red, 2 white
D. 4 white
Answer Explanation
2 red, 2 white.
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.
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Q #4: Which of the following are structural features of the trachea?
A. C-shaped cartilage
B. Smooth muscle fibers
C. Cilia
D. All of the above
Answer Explanation
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Q #5: In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will produce only offspring with smooth leaves?
A. Ff x ff
B. Ff x Ff
C. FF x FF
D. ff x ff
Answer Explanation
Crossing is the breeding of parents to produce an offspring. Given that f is a recessive allele of smooth leaves while F is the dominant allele of fuzzy leaves. Therefore, where there is F crossing with f, the offspring will have fuzzy leaves over smooth one.
Therefore, for an offspring to have smooth leaves, ff and ff must cross to produce an offspring with smooth leaves. -
Q #6: Base your answer on the graph and on your knowledge of biology. Which is a true statement about the relationship between pH and enzyme action?
A. All enzymes work best at a neutral pH.
B. Adding more acid does not affect the rate of activity of an enzyme.
C. Enzymes function only in a pH range of 4.0 to 5.5.
D. The activity of an enzyme is affected by pH.
Answer Explanation
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Q #7: Contraction of the external intercostal muscles causes which of the following to occur?
A. The diaphragm moves downward
B. The rib cage is compressed
C. The thoracic cavity volume decreases
D. The ribs and sternum move upward
Answer Explanation
The intercostal muscles are muscles are located along the ribs. The intercostal muscles assist in respiration mechanically. This allows the expansion and contraction of the thorax.
Contraction of the external intercostal muscle causes the ribs and sternum move upward. -
Q #8: The Life Cycle of HIV Which of the following allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host T-cell after the AIDS virus enters the cell?
A. Receptor proteins located on the surface of the virus
B. The protein that makes up the capsid of the virus
C. Reverse transcriptase, an enzyme encoded by the virus
D. The phospholipids found on the envelope of the virus
Answer Explanation
The AIDS virus (HIV virus) is Class VI or Group VI in the Baltimore Classification. Based on the Baltimore Classification, this specifically involves the reverse transcriptase enzyme and it is encoded by the virus.
This is the enzyme that will produce DNA molecules from the viral RNA. This is the mechanism involved where it will use the reverse transcriptase enzyme to insert viral DNA into the genetic material of the host cell.
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Q #9: Which of the following best describes the result of using a catalyst in a chemical reaction?
A. A more desirable product is often formed
B. The reaction is completed in a shorter amount of time
C. The yield of product is increased
D. A greater amount of energy is released by the reaction
Answer Explanation
A catalyst is substance that speeds up the rate of converting reactants to products. They do by decreasing the activation energy of a reaction. If a catalyst increases the rate of reaction, then it means that the reaction takes a smaller time to come into completion.
Catalysts can be metals, ions or biological also known as enzymes. Catalysts are not consumed when the reaction is taking place. -
Q #10: Metabolism of proteins Which of the following substances is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia?
A. Sebum
B. Urea
C. Lysozymes
D. Water
Answer Explanation
Proteins are nitrogen-based compounds, which when broken down release ammonia. Ammonia is a toxic substance to the body, and sebaceous glands coverts it to urea.
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