Genetics Unit Post-assessment (Grade 8)
Genetics Unit Post-Assessment (Grade 8)
- 1.
A(n) is a segment of DNA that carries the instructions for producing a specific trait (Intermediate Core Curriculum 2.2a)
- A.
Chromosome
- B.
Karyotype
- C.
Enzyme
- D.
Gamete
- E.
Gene
Correct Answer
E. GeneExplanation
A gene is a segment of DNA that carries the instructions for producing a specific trait. Genes are responsible for determining the characteristics and traits of an organism, such as eye color, height, and blood type. They provide the instructions for the production of proteins, which are essential for the functioning of cells and the development of traits. Genes can be passed down from parents to offspring through reproduction, allowing traits to be inherited.Rate this question:
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- 2.
Kernel corn is a trait determined by two alleles. The dominant allele (P) produces a purple color, and the recessive allele (p) produces a yellow color. The diagram below shows an ear of corn produced by crossing two corn plants. The shaded kernels are purple, and the unshaded ones are yellow. The yellow corn kernels can best be described as (Intermediate Core Curriculum 2.2b).
- A.
Homozygous dominant
- B.
Hybrid
- C.
Heterozygous
- D.
Homozygous recessive
- E.
Codominant
Correct Answer
D. Homozygous recessiveExplanation
The yellow corn kernels can be best described as homozygous recessive because the yellow color is produced by the recessive allele (p). In order for an individual to have yellow kernels, they must have two copies of the recessive allele, making them homozygous recessive.Rate this question:
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- 3.
Pea plants come in two sizes – tall plants and dwarf plants. The dominant allele (T) produces tall pea plants, and the recessive allele (t) produces dwarf pea plants. The Punnett Square below shows a cross between tall and dwarf pea plants. What is the probability that the offspring of this cross are homozygous recessive (Intermediate Core Curriculum 2.2c).
- A.
0%
- B.
25%
- C.
50%
- D.
75%
- E.
100%
Correct Answer
C. 50%Explanation
The Punnett Square shows that there are four possible combinations of alleles in the offspring: TT, Tt, Tt, and tt. Since the question asks for the probability of the offspring being homozygous recessive (tt), there is only one out of the four combinations that results in this genotype. Therefore, the probability is 1 out of 4, which is equivalent to 25%.Rate this question:
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- 4.
Below is a pedigree for an inherited heart disease. If the father labeled II 2 is heterozygous, what is the probability that the child labeled III 1 would be a carrier of heart disease (Intermediate Core Curriculum 2.2c)?
- A.
0%
- B.
25%
- C.
50%
- D.
75%
- E.
100%
Correct Answer
C. 50%Explanation
If the father labeled II 2 is heterozygous, it means he carries one copy of the gene for the heart disease and one normal copy. The child labeled III 1 will inherit one copy of the gene from the father and one from the mother. Since the father is heterozygous, there is a 50% chance that he will pass on the gene for the heart disease to the child. Therefore, the probability that the child labeled III 1 would be a carrier of the heart disease is 50%.Rate this question:
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- 5.
Which of the following is an example of how genes can be modified by the environment (Standard 2.1a):
- A.
Pleiotropy (You may inherit a gene for the complex of symptoms that are collectively called sickle-cell anemia).
- B.
Incomplete Penetrance (You may inherit the gene for diabetes but never get the disease unless you become overweight)
- C.
Epistasis (Your dog inherits a dominant allele that determines whether the fur will have dark pigment and a different allele that determines how dark the pigment will be)
- D.
Polygenic Traits (You inherit many different genes which combined effects determines your skin color).
- E.
Codominance (A cow inherits two alleles that make a positive contribution to the phenotype resulting in a black and white coat).
Correct Answer
B. Incomplete Penetrance (You may inherit the gene for diabetes but never get the disease unless you become overweight)Explanation
Incomplete penetrance is an example of how genes can be modified by the environment. In this case, an individual may inherit the gene for diabetes but will only develop the disease if they become overweight. This shows that the expression of the gene is influenced by external factors, such as weight gain, rather than being solely determined by genetics. The environment plays a role in whether or not the gene is expressed and the disease is manifested.Rate this question:
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- 6.
Which statement describes the work of Gregor Mendel (Standard 2.1a)?
- A.
He developed some basic principles of heredity without having knowledge of chromosomes.
- B.
He developed the microscope for the study of genes in pea plants.
- C.
He explained the principle of dominance on the basis of the gene-chromosome theory.
- D.
He used his knowledge of gene mutations to help explain the appearance of new traits in organisms.
- E.
He studied the beaks of finches which helped him to develop the theory of evolution by natural selection.
Correct Answer
A. He developed some basic principles of heredity without having knowledge of chromosomes.Explanation
Gregor Mendel developed some basic principles of heredity without having knowledge of chromosomes. This means that Mendel was able to make significant discoveries about how traits are passed down from parents to offspring without understanding the role that chromosomes play in this process. Mendel's experiments with pea plants allowed him to establish fundamental principles such as the law of segregation and the law of independent assortment, which laid the foundation for modern genetics. His work was groundbreaking and formed the basis for our understanding of genetics today.Rate this question:
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- 7.
Some individuals with blood group A may inherit the genes for dimples, while other individuals with blood group A may inherit the genes for no dimples. This can best be explained by the principle of (Standard 2.1b)?
- A.
Dominance
- B.
Multiple alleles
- C.
Independent assortment
- D.
Incomplete dominance
- E.
Segregation
Correct Answer
C. Independent assortmentExplanation
The principle of independent assortment states that different traits are inherited independently of each other. In this case, the presence or absence of dimples is not directly related to the blood group A. Therefore, some individuals with blood group A may inherit the genes for dimples, while others may inherit the genes for no dimples. This suggests that the inheritance of blood group A and the presence or absence of dimples are independent of each other and follow the principle of independent assortment.Rate this question:
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- 8.
Chromosomes normally occur as homologous pairs in (Standard 2.1c):
- A.
A sperm cell
- B.
An egg cell
- C.
A zygote
- D.
A gamete
- E.
A haploid cell
Correct Answer
C. A zygoteExplanation
Chromosomes normally occur as homologous pairs in a zygote. A zygote is formed when a sperm cell fertilizes an egg cell, resulting in the fusion of their genetic material. Homologous pairs of chromosomes contain similar genes, one from each parent, and are responsible for determining an individual's traits. Therefore, it is in the zygote stage that chromosomes are paired and present in their homologous form.Rate this question:
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- 9.
Which of the following statements is true (Standard 2.1c)?
- A.
Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes.
- B.
Gene linkage is an exception to Mendel’s Law of Dominance
- C.
Genetic recombination involves both gene linkage and chromosome mapping.
- D.
Polyploid plants are avoided by plant growers because they are almost always lethal.
- E.
Each somatic cell in the human body has a different number of chromosomes depending on the function of the cell.
Correct Answer
A. Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes.Explanation
Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes. This statement is true because chromosome maps are created based on the frequency of recombination events between genes during genetic recombination. The closer two genes are on a chromosome, the less likely they are to undergo recombination. By measuring the frequency of recombination events, scientists can determine the relative positions of genes on a chromosome. The percentage values on a chromosome map represent the likelihood of recombination occurring between genes, not the actual physical distances between them.Rate this question:
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- 10.
Breeders have developed a variety of chicken that has no feathers. Which methods were most likely used to produce this variety (Standard 2.2a)?
- A.
Artificial selection and inbreeding
- B.
Grafting and hybridization
- C.
Regeneration and incubation
- D.
Vegetative propagation and binary fission
- E.
Test cross and polyploidy
Correct Answer
A. Artificial selection and inbreedingExplanation
The correct answer is artificial selection and inbreeding. This is because breeders have selectively bred chickens with no feathers by choosing individuals with this trait and breeding them together. Over time, this process of artificial selection and inbreeding has resulted in a variety of chicken that has no feathers. Grafting, hybridization, regeneration, incubation, vegetative propagation, binary fission, test cross, and polyploidy are not relevant methods for producing this variety of chicken.Rate this question:
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- 11.
Rate, on a scale of 1 – 4, 1 being the lowest and 4 being the highest, how much you already know about genetics.
Correct Answer
1
2
3
4Explanation
The answer to this question is 1,2,3,4 because it allows the respondent to rate their level of knowledge on genetics on a scale of 1 to 4. This scale provides a range of options for the respondent to choose from, allowing them to indicate whether they have a low level of knowledge (1) or a high level of knowledge (4) on the subject.Rate this question:
- 12.
Rate, on a scale of 1 – 4, 1 being the lowest and 4 being the highest, how interested are you in genetics.
Correct Answer
1
2
3
4Explanation
This question is asking the respondent to rate their level of interest in genetics on a scale of 1 to 4. The answer "1,2,3,4" indicates that the respondent is equally interested in all levels, ranging from the lowest (1) to the highest (4).Rate this question:
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