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TEAS 7 Science Custom TEAS Science Practice Test 1 Punnett square In a certain plant, re...

Punnett square 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. 4 red, 0 white

B. 2 red, 2 white

C. 1 red, 3 white

D. 3 red, 1 white

Answer Explanation:

We use the Punnet square to find the population of the resulting offspring from the crossing of a plant heterozygous for red flowers with a plant with white flowers.

Let R be the dominant allele for red while r is the recessive allele color for red. Therefore, the phenotype for parent 1 which is heterozygous for red flower will be Rr and the second parent with white flowers will be rr.

We cross the two phenotypes in a Punnet square as follows

 

r

r

R

Rr

Rr

r

rr

rr

 

Thus, there are 2 heterozygous offspring with red flowers and 2 offspring with white flowers.

Therefore, the Correct Answer is B.

More Questions on TEAS 7 Science

  • Q #1: Punnett square 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. 4 red, 0 white

    B. 2 red, 2 white

    C. 1 red, 3 white

    D. 3 red, 1 white

    Answer Explanation

    We use the Punnet square to find the population of the resulting offspring from the crossing of a plant heterozygous for red flowers with a plant with white flowers.

    Let R be the dominant allele for red while r is the recessive allele color for red. Therefore, the phenotype for parent 1 which is heterozygous for red flower will be Rr and the second parent with white flowers will be rr.

    We cross the two phenotypes in a Punnet square as follows

     

    r

    r

    R

    Rr

    Rr

    r

    rr

    rr

     

    Thus, there are 2 heterozygous offspring with red flowers and 2 offspring with white flowers.

  • Q #2: If a portion of strand of DNA bases reads 5’ AGCTAGCGT 3’, what would the sequence of bases on the complementary strand read?

    A. 5’ UCGAUCGCA 3’

    B. 3’ TCGATCGCA 5’

    C. 5’ TCGUTCGCU 3’

    D. 3’ AGCTAGCGT 5’

    Answer Explanation

    The complimentary base pairing of DNA states that A pairs with T while C pairs with G. From the give sequence, the complimentary DNA strand will be 3’ TCGATCGCA 5’

  • Q #3: Building blocks of proteins Which of the following organic molecules contain both an amine and carboxyl group?

    A. Lipids

    B. Proteins

    C. Cellulose

    D. Chitin

    Answer Explanation

    The basic building block of the protein is ammonia, which comprises of ammino group -NH2 and a carboxyl group, -COOH.

  • 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

  • Q #5: 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.

  • Q #6: 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.

     

  • Q #7: Which of these infectious agents do not have nucleic acid?

    A. viroids

    B. viruses

    C. bacteria

    D. prions

    Answer Explanation

  • Q #8: Which of the following are used to determine a person’s DNA sequence?

    A. Genes

    B. Enzymes

    C. Hormones

    D. Blood types

    Answer Explanation

    A gene is the basic physical and functional unit of heredity and it is the DNA that make up genes. Enzymes are biological catalysts that speed up metabolic and cellular reactions in our bodies. Hormones are responsible for controlling the action of certain cells or organs in our bodies. Blood types are of four types, A, B, AB, and O.

  • Q #9: Which of the following statements best supports the hypothesis that viruses can cause cancer?

    A. Cellular DNA has sequences related to viral sequences

    B. Cancerous and normal cells share genetic sequences

    C. Genes that regulate cell division are found in some viruses

    D. Viruses and cancer cells both replicate rapidly

    Answer Explanation

    Cancer is a condition caused by unregulated division of abnormal cells in parts of the body. For a virus to survive in an organism, it must enter into the host’s cell and take control of the cell’s most activities in order to be able to reproduce and replicate.

    Some of the viruses achieve this by inserting their DNA or RNA to that of the host cell. This has a highly likelihood of affecting the DNA or RNA of a host (living organism) which alters their genes, which may lead to host cells becoming cancerous.

    For this reason, viruses can cause cancer because the genes that regulate cell division in host cell are found in some viruses.

  • Q #10: Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?

    A. Diffusion down a concentration gradient

    B. Conversion of carbon monoxide

    C. Passive transport using carrier proteins

    D. Active transport using energy

    Answer Explanation

    Carbon dioxide moves from the blood to the alveoli through the process of diffusion. The blood has a high concentration of carbon dioxide than the alveoli.
    Therefore, carbon dioxide diffuses from blood to alveoli through the cell membrane.

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