Genetics Unit Pre-assessment (Grade 8)
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A(n) is a segment of DNA that carries the instructions for producing a specific trait (Intermediate Core Curriculum 2.2a)
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Chromosome
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Karyotype
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Enzyme
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Gamete
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Gene
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Are you an 8th grader and have just gotten introduced to all things genetics? One thing you should know is how traits are passed from parents to offspring. If so then the genetics unit pre-assessment quiz below is exactly what you need to ensure that you have understood all you covered so far. Do give it a try and see See morehow well you will do. All the best!
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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).
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Homozygous dominant
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Hybrid
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Heterozygous
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Homozygous recessive
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Codominant
Correct Answer
A. Homozygous recessiveExplanation
The yellow corn kernels can be best described as homozygous recessive because they have the genotype pp, meaning they have two copies of the recessive allele (p) for yellow color. This is because the purple color is determined by the dominant allele (P), so for a kernel to be purple it must have at least one copy of the dominant allele. Since the yellow kernels are not shaded, it means they do not have any copies of the dominant allele and are therefore 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).
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0%
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25%
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50%
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75%
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100%
Correct Answer
A. 50%Explanation
The Punnett Square shows that the cross between tall and dwarf pea plants results in offspring with genotypes TT, Tt, and tt. Homozygous recessive individuals have the genotype tt. Since there is only one possible genotype that is homozygous recessive out of the four possible genotypes (tt, TT, Tt, and Tt), the probability of the offspring being homozygous recessive is 1 out of 4, which is equivalent to 25%. Therefore, the correct answer is 25%.Rate this question:
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- 4.
Below is a pedigree for an inherited heart disease. What is the probability that their child F would have the inherited heart disease (Intermediate Core Curriculum 2.2c)?
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0%
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25%
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50%
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75%
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100%
Correct Answer
A. 50%Explanation
Based on the given pedigree, both parents (D and E) are carriers of the inherited heart disease since they have an affected child (C) and unaffected child (F). Therefore, there is a 50% chance that their child F would have the inherited heart disease.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)?
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Pleiotropy (You may inherit a gene for the complex of symptoms that are collectively called sickle-cell anemia).
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Incomplete Penetrance (You may inherit the gene for diabetes but never get the disease unless you become overweight)
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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)
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Polygenic Traits (You inherit many different genes which combined effects determines your skin color).
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Codominance (A cow inherits two alleles that make a positive contribution to the phenotype resulting in a black and white coat).
Correct Answer
A. Incomplete Penetrance (You may inherit the gene for diabetes but never get the disease unless you become overweight)Explanation
Incomplete penetrance refers to a situation where an individual inherits a gene for a certain trait or disease, but the trait or disease only manifests under certain environmental conditions. In this case, the gene for diabetes is inherited, but the disease only occurs if the individual becomes overweight. This demonstrates how the environment, specifically weight gain, can modify the expression of the gene and determine whether the disease develops or not.Rate this question:
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- 6.
Which statement describes the work of Gregor Mendel (Standard 2.1a)?
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He developed some basic principles of heredity without having knowledge of chromosomes.
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He developed the microscope for the study of genes in pea plants.
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He explained the principle of dominance on the basis of the gene-chromosome theory.
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He used his knowledge of gene mutations to help explain the appearance of new traits in organisms.
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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 is known as the father of modern genetics. He conducted experiments with pea plants and discovered the basic principles of heredity, such as the laws of segregation and independent assortment. These principles explain how traits are passed from parents to offspring. At the time, Mendel did not have knowledge of chromosomes or genes, as they were not yet discovered. Therefore, the statement "He developed some basic principles of heredity without having knowledge of chromosomes" accurately describes Mendel's work.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)?
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Dominance
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Multiple alleles
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Independent assortment
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Incomplete dominance
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Segregation
Correct Answer
A. Independent assortmentExplanation
Independent assortment refers to the random distribution of genes during the formation of gametes. In this case, the inheritance of blood group A and the presence or absence of dimples are two separate traits that are not linked. Therefore, individuals with blood group A can inherit the genes for dimples or no dimples independently of their blood type. This is consistent with the principle of independent assortment.Rate this question:
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- 8.
Chromosomes normally occur as homologous pairs in (Standard 2.1c):
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A sperm cell
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An egg cell
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A zygote
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A gamete
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A haploid cell
Correct Answer
A. 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 are pairs of chromosomes that contain the same genes, although they may have different versions of those genes. These homologous pairs are important for genetic diversity and the inheritance of traits. Therefore, it is in the zygote stage that chromosomes are present as homologous pairs.Rate this question:
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- 9.
Which of the following statements is true (Standard 2.1c)?
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Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes.
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Gene linkage is an exception to Mendel’s Law of Dominance Genetic recombination involves both gene linkage and chromosome mapping.
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Polyploid plants are avoided by plant growers because they are almost always lethal.
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Each somatic cell in the human body has a different number of chromosomes depending on the function of the cell.
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Genetic recombination involves both gene linkage and chromosome mapping.
Correct Answer
A. Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes.Explanation
The statement "Chromosome map percentages are not actual chromosome distances, but represent the relative position of genes" is true. Chromosome maps are used to represent the relative positions of genes on a chromosome, but the distances between the genes on the map do not necessarily correspond to the actual physical distances on the chromosome. The map percentages are based on the frequency of genetic recombination events between genes, which can vary depending on factors such as the distance between the genes and the presence of gene linkage. Therefore, the map percentages are relative measures of gene position rather than precise measurements of chromosome distances.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)?
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Artificial selection and inbreeding
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Grafting and hybridization
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Regeneration and incubation
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Vegetative propagation and binary fission
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Test cross and polyploidy
Correct Answer
A. Artificial selection and inbreedingExplanation
The development of a chicken variety with no feathers is most likely achieved through artificial selection and inbreeding. Artificial selection involves selecting and breeding individuals with desired traits, in this case, the absence of feathers. Inbreeding is the breeding of closely related individuals to maintain or enhance specific traits. By selectively breeding chickens without feathers and then mating them with closely related individuals, breeders can increase the frequency of the no-feather trait in the population.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 knowledge of genetics on a scale of 1 to 4. A rating of 1 would indicate that the person has very little knowledge of genetics, while a rating of 4 would suggest a high level of knowledge. By including all the options from 1 to 4, the question covers a wide range of possible knowledge levels and allows the respondent to provide a more accurate assessment of their understanding of genetics.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
The given answer options range from 1 to 4, allowing the respondent to rate their interest in genetics on a scale. Option 1 indicates the lowest level of interest, option 2 indicates a slightly higher level of interest, option 3 indicates a moderate level of interest, and option 4 indicates the highest level of interest. The respondent can choose any of these options based on their personal level of interest in genetics.Rate this question:
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Mar 21, 2023Quiz Edited by
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Apr 03, 2010Quiz Created by
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