8th Grade Science Test Review
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This is a practice test designed to help you with your test on Tuesday.
Questions and Answers
- 1.
An organelle enclosed in a membrane that contains DNA.
- A.
Cytoplasm
- B.
Cell wall
- C.
Chromosome
- D.
Nucleus
Correct Answer
D. NucleusExplanation
The correct answer is nucleus. The nucleus is an organelle enclosed in a membrane that contains DNA. It is often described as the control center of the cell because it houses the cell's genetic material and controls the cell's activities by regulating gene expression. The nucleus plays a crucial role in cell division, DNA replication, and protein synthesis.Rate this question:
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- 2.
The genetic material that determines inherited characteristics.
- A.
Allele
- B.
Gene
- C.
DNA
- D.
Chromosome
Correct Answer
C. DNAExplanation
DNA, or deoxyribonucleic acid, is the correct answer because it is the genetic material that carries the instructions for the development and functioning of living organisms. DNA is composed of genes, which are segments of DNA that code for specific traits or characteristics. Alleles are different versions of a gene, and chromosomes are structures that contain DNA. However, DNA is the fundamental molecule that carries the genetic information and determines inherited characteristics.Rate this question:
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- 3.
The instructions for an inherited trait.
- A.
Gene
- B.
Trait
- C.
DNA
- D.
Allele
Correct Answer
A. GeneExplanation
A gene is the correct answer because it is responsible for carrying the instructions for an inherited trait. Genes are segments of DNA that contain the information needed to produce specific traits or characteristics. They are located on chromosomes and are made up of alleles, which are different forms of a gene. Therefore, a gene is the fundamental unit of heredity and is responsible for transmitting genetic information from one generation to the next.Rate this question:
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- 4.
The different forms of a gene.
- A.
Gene
- B.
DNA
- C.
Trait
- D.
Allele
Correct Answer
D. AlleleExplanation
Alleles are different forms or variants of a gene. Genes are segments of DNA that contain instructions for building and maintaining an organism. Traits, such as eye color or height, are determined by genes. Each gene can have different versions called alleles, which can result in variations in the trait. For example, the gene for eye color may have alleles for blue, brown, or green eyes. Therefore, the correct answer is allele.Rate this question:
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- 5.
Identify the following: Dd
- A.
Heterozygous
- B.
Homozygous
- C.
Phenotype
- D.
Gene
Correct Answer
A. HeterozygousExplanation
Heterozygous refers to an individual having two different alleles for a particular gene. This means that the individual has inherited different versions of the gene from their parents. In the context of genetics, heterozygous individuals often exhibit a mixed or intermediate phenotype, as the two different alleles may have different effects on the trait they control.Rate this question:
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- 6.
Identify the following: rr
- A.
Homozygous dominant
- B.
Heterozygous recessive
- C.
Homozygous recessive
- D.
Heterozygous dominant
Correct Answer
C. Homozygous recessiveExplanation
The term "homozygous recessive" refers to an individual who has two copies of the same recessive allele for a particular trait. In this case, the individual has two copies of the recessive allele, which means that they will express the recessive trait. This is in contrast to "homozygous dominant," where an individual has two copies of the dominant allele and will express the dominant trait. "Heterozygous recessive" refers to an individual who has one copy of the recessive allele and one copy of the dominant allele, and "heterozygous dominant" refers to an individual who has one copy of the dominant allele and one copy of the recessive allele.Rate this question:
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- 7.
An organism’s appearance is known as its
Correct Answer
phenotype
PhenotypeExplanation
The term "phenotype" refers to an organism's physical appearance or observable traits. It includes characteristics such as hair color, eye color, height, and other visible features. The phenotype is determined by a combination of genetic factors and environmental influences. It is an important concept in genetics and biology as it helps in understanding how traits are expressed and passed on from one generation to another.Rate this question:
- 8.
The combination of inherited alleles together form an organism’s .
Correct Answer
genotype
GenotypeExplanation
The combination of inherited alleles together form an organism's genotype. The genotype refers to the specific genetic makeup of an individual, which includes all the genes and alleles they have inherited from their parents. It determines the traits and characteristics that an organism will have.Rate this question:
- 9.
DNA is made of subunits called
Correct Answer
nucleotides
NucleotidesExplanation
DNA is made up of subunits called nucleotides. Nucleotides are the building blocks of DNA and consist of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). These nucleotides join together through covalent bonds between the sugar and phosphate groups, forming a long chain called a polynucleotide. The sequence of nucleotides in DNA carries the genetic information that determines the characteristics and functions of living organisms. Therefore, nucleotides are essential components of DNA.Rate this question:
- 10.
The passing of traits from parents to offspring.
- A.
Genes
- B.
DNA
- C.
Heredity
- D.
Purebred
Correct Answer
C. HeredityExplanation
Heredity refers to the passing of traits from parents to offspring. It involves the transmission of genetic information, which is encoded in genes and carried by DNA. Heredity is responsible for the similarities and differences between individuals within a species and is the basis for inheritance. Purebred refers to an organism that is bred from parents of the same breed, which is a result of controlled heredity.Rate this question:
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- 11.
A trait or allele expressed only when two recessive alleles for the same characteristic are inherited.
Correct Answer
recessive
recessiveExplanation
This answer refers to the concept of recessive alleles. A recessive allele is only expressed when an individual inherits two copies of the recessive allele for a specific trait. In this case, the given answer indicates that both alleles for the characteristic are recessive, meaning that the trait will only be expressed if both alleles inherited are recessive.Rate this question:
- 12.
Used to organize all the possible genotype combinations of offspring from particular parents.
- A.
Karyotype
- B.
Family tree
- C.
Punnett Square
Correct Answer
C. Punnett SquareExplanation
A Punnett Square is a tool used in genetics to predict the possible genotype combinations of offspring from specific parents. It is a grid-like diagram that organizes the different alleles from each parent and allows for the calculation of the probability of different genetic outcomes. By using the Punnett Square, geneticists can better understand the inheritance patterns and potential traits that offspring may inherit.Rate this question:
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- 13.
Different forms of a characteristic.
Correct Answer
trait
TraitExplanation
The correct answer is "trait, Trait". In this context, "trait" and "Trait" are both forms of the same characteristic. The lowercase "trait" refers to a general characteristic or quality, while the capitalized "Trait" could refer to a specific trait or a trait that is being emphasized or highlighted. Both forms are correct and can be used interchangeably depending on the context or personal preference.Rate this question:
- 14.
A feature that has different forms in a population.
Correct Answer
characteristic
CharacteristicExplanation
A characteristic refers to a feature that can vary in different forms within a population. It is a distinguishing attribute or quality that sets individuals or groups apart from one another. This term can be used to describe traits, behaviors, or physical attributes that are unique to certain individuals or groups within a population.Rate this question:
- 15.
This is an image of a _________________.
- A.
Genetic map
- B.
Karyotype
- C.
Pedigree
- D.
Genotype
Correct Answer
B. KaryotypeExplanation
This image is likely a karyotype because it shows a visual representation of an individual's chromosomes arranged in pairs according to size, shape, and banding patterns. Karyotypes are commonly used in genetics to analyze and diagnose chromosomal abnormalities or disorders.Rate this question:
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- 16.
A genetic disorder caused from an added chromosome to chromosome 21.
- A.
Down Syndrome
- B.
Cri-Du-Chat syndrome
- C.
Chromosome 21 Disorder
Correct Answer
A. Down SyndromeExplanation
Down Syndrome is a genetic disorder that occurs when there is an extra copy of chromosome 21. This additional chromosome disrupts the normal development and causes various physical and intellectual disabilities. The presence of an extra chromosome affects the way the body and brain develop, leading to characteristic features such as low muscle tone, upward slanting eyes, a flattened facial profile, and intellectual disability. Down Syndrome is the most common chromosomal disorder and is typically diagnosed at birth or during early childhood through genetic testing.Rate this question:
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- 17.
A cross of two traits.
- A.
Dihybrid cross
- B.
Monohybrid cross
- C.
Genetic cross
Correct Answer
A. Dihybrid crossExplanation
A dihybrid cross refers to the breeding of two individuals that are heterozygous for two different traits. This means that each individual carries two different versions of the genes for the traits being studied. In this type of cross, the offspring will inherit a combination of these genes, resulting in the expression of both traits. This is different from a monohybrid cross, which involves the breeding of two individuals that are heterozygous for only one trait. A genetic cross is a general term that encompasses both monohybrid and dihybrid crosses.Rate this question:
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- 18.
The outer boundary of the cell designed to regulate what comes and out of the cell.
- A.
Nucleus
- B.
Cytoplasm
- C.
Membrane
Correct Answer
C. MembraneExplanation
The outer boundary of the cell, known as the cell membrane, is responsible for regulating the movement of substances in and out of the cell. It acts as a barrier, allowing certain molecules to pass through while preventing others from entering or leaving the cell. The membrane is made up of a phospholipid bilayer, which provides a selective barrier that helps maintain the cell's internal environment and protect it from external factors. Therefore, the membrane is crucial for maintaining homeostasis and controlling the transport of molecules in and out of the cell.Rate this question:
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- 19.
Erwin Chargaff's base pairing rule state that ___________ has an equal proportion to ___________, and ____________ to _____________.
- A.
Adenine to guanine and cytosine to thymine
- B.
Adenine to thymine and cytosine to guanine
- C.
Adenine to cytosine and guanine to thymine
Correct Answer
B. Adenine to thymine and cytosine to guanineExplanation
Erwin Chargaff's base pairing rule states that adenine has an equal proportion to thymine, and cytosine has an equal proportion to guanine. This means that in a DNA molecule, the amount of adenine is always equal to the amount of thymine, and the amount of cytosine is always equal to the amount of guanine. This rule is essential for understanding the structure and replication of DNA.Rate this question:
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- 20.
A nucleotide is composed of
- A.
A sugar, base and phosphate
- B.
A sugar and base
- C.
A base and phosphate
- D.
A dna, base and gene
Correct Answer
A. A sugar, base and pHospHateExplanation
A nucleotide is composed of a sugar, base, and phosphate. The sugar component provides the backbone structure of the nucleotide, while the base component is responsible for encoding genetic information. The phosphate group is attached to the sugar and provides a negative charge, allowing nucleotides to link together and form the DNA or RNA molecule. This combination of sugar, base, and phosphate forms the basic building block of nucleic acids.Rate this question:
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- 21.
Scientist which contributed to the discovery of the DNA structure were: James Watson, Francis Crick, and Rosalind Franklin.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because James Watson, Francis Crick, and Rosalind Franklin were indeed scientists who made significant contributions to the discovery of the DNA structure. James Watson and Francis Crick are credited with proposing the double helix structure of DNA in 1953, while Rosalind Franklin's X-ray crystallography images provided crucial evidence for their model. Together, their work laid the foundation for our understanding of the DNA molecule and its role in genetics.Rate this question:
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- 22.
Rr x rr R= Round r= wrinkled What percentage of the offspring will be round? ___________
- A.
25%
- B.
75%
- C.
50%
- D.
100%
Correct Answer
C. 50%Explanation
In this question, the genotype of one parent is represented by "Rr" (Round) and the genotype of the other parent is represented by "rr" (wrinkled). The uppercase "R" represents the dominant allele for round shape, while the lowercase "r" represents the recessive allele for wrinkled shape. When these two genotypes are crossed, the possible genotypes of the offspring are "Rr" and "rr". Since "R" is dominant, any offspring with at least one "R" allele will have a round shape. Therefore, 50% of the offspring will be round.Rate this question:
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- 23.
A homozygous round seeded plant is crossed with a homozygous wrinkled seeded plant. What are the genotypes of the parents? R= Round r=wrinkled
Correct Answer
RrExplanation
The correct answer is Rr. In this question, it is stated that a homozygous round seeded plant is crossed with a homozygous wrinkled seeded plant. The genotype of a homozygous round seeded plant is RR, as it has two copies of the dominant allele R. The genotype of a homozygous wrinkled seeded plant is rr, as it has two copies of the recessive allele r. When these two plants are crossed, the possible genotypes of the parents are Rr (one copy of the dominant allele R and one copy of the recessive allele r).Rate this question:
- 24.
In rabbits, grey hair is dominant to white hair. Also in rabbits, black eyes are dominant to red eyes. These letters represent the genotypes of the rabbits: GG = gray hair Gg = gray hair gg = white hair BB = black eyes Bb = black eyes bb = red eyes A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb The square is set up below. Fill it out and determine the phenotypes and proportions in the offspring. Question: How many out of 16 have grey fur and black eyes? ________
Correct Answer
8
eightExplanation
In this question, the male rabbit has the genotype GGbb, which means it has gray hair (dominant) and red eyes (recessive). The female rabbit has the genotype ggBb, which means it has white hair (recessive) and black eyes (dominant). When these two rabbits are crossed, the Punnett square can be set up to determine the possible genotypes and phenotypes of the offspring.
The Punnett square would look like this:
| Gb | Gb |
---|----|----|---
gB | GgBb | GgBb |
gB | Ggbb | Ggbb |
From the Punnett square, we can see that 8 out of the 16 possible offspring have the genotype GgBb, which means they have gray fur (dominant) and black eyes (dominant). Therefore, the answer is 8 (or eight).Rate this question:
- 25.
GG = gray hair Gg = gray hair gg = white hair BB = black eyes Bb = black eyes bb = red eyes A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb Question: How many out of 16 have white fur and black eyes? ________
Correct Answer
0
zeroExplanation
In this question, the genotype of the male rabbit is GGbb, which means it has gray hair (G) and red eyes (bb). The genotype of the female rabbit is ggBb, which means it has white hair (gg) and black eyes (Bb). When these two rabbits are crossed, the offspring will inherit one allele from each parent for each trait. Since the male rabbit has the dominant allele for hair color (G) and the female rabbit has the recessive allele for hair color (gg), all the offspring will have gray hair. Similarly, since the male rabbit has the recessive allele for eye color (bb) and the female rabbit has the dominant allele for eye color (Bb), all the offspring will have black eyes. Therefore, none of the offspring will have white fur and black eyes.Rate this question:
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Mar 21, 2023Quiz Edited by
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