BIOL 210 | BIOL210 Module 1: Genetics Updated
and Latest Questions and Correct Answers with
Rationale - Portage Learning
1. Which of the following serves as the basic building block of a DNA molecule?
A. Amino acid
B. Monosaccharide
C. Fatty acid
D. Nucleotide
Correct Answer: D
Explanation: A nucleotide is the fundamental structural unit of DNA consisting of a sugar,
phosphate, and nitrogenous base. Amino acids are the building blocks of proteins rather
than nucleic acids. Fatty acids are components of lipids used for energy storage and
membrane structure. Monosaccharides are simple sugars that serve as the building blocks
for complex carbohydrates. Therefore, the nucleotide is the only option that directly
composes the genetic material DNA.
2. In the DNA double helix, which nitrogenous base pairs with Cytosine?
A. Guanine
B. Thymine
C. Uracil
D. Adenine
Correct Answer: A
Explanation: According to base-pairing rules, Guanine always forms three hydrogen bonds
with Cytosine in DNA. Adenine pairs specifically with Thymine in DNA molecules to
maintain the double helix width. Uracil is a nitrogenous base found only in RNA where it
replaces Thymine. Thymine is a pyrimidine that pairs with the purine Adenine in a
standard DNA structure. Understanding these complementary pairs is essential for
predicting DNA sequences and replication patterns.
3. What is the specific physical location of a gene on a chromosome called?
A. Allele
B. Locus
C. Centromere
D. Telomere
,Correct Answer: B
Explanation: The locus refers to the fixed position on a chromosome where a particular
gene or genetic marker is located. An allele is a variant form of a gene rather than the
physical location itself. The centromere is the constricted region of a chromosome that
joins sister chromatids together. Telomeres are the repetitive DNA sequences located at the
very ends of linear chromosomes. Identifying the locus is a critical step in genetic mapping
and studying inheritance patterns.
4. How many pairs of autosomes are found in a typical human somatic cell?
A. 22
B. 46
C. 23
D. 1
Correct Answer: A
Explanation: Human somatic cells contain a total of 23 pairs of chromosomes, of which 22
pairs are autosomes. The 23rd pair consists of the sex chromosomes which determine the
biological sex of the individual. A total count of 46 individual chromosomes exists in a
diploid human cell. Only one pair of chromosomes serves as the sex-determining pair in
humans. Thus, the correct number of autosomal pairs is 22.
5. Which structure is formed when DNA wraps around histone proteins?
A. Centrosome
B. Ribosome
C. Nucleosome
D. Lysosome
Correct Answer: C
Explanation: A nucleosome is the basic unit of DNA packaging in eukaryotes consisting of
a segment of DNA wound around eight histone proteins. Ribosomes are cellular machines
responsible for protein synthesis rather than DNA storage. Centrosomes are organelles that
serve as the main microtubule-organizing centers during cell division. Lysosomes are
membrane-bound organelles containing digestive enzymes for breaking down waste
materials. The formation of nucleosomes is the first level of folding required to fit DNA into
the nucleus.
6. What term describes the genetic makeup of an organism for a specific trait?
A. Genotype
B. Phenotype
, C. Karyotype
D. Haplotype
Correct Answer: A
Explanation: The genotype represents the specific set of alleles an individual carries for a
particular gene. The phenotype refers to the observable physical or physiological
characteristics resulting from the genotype. A karyotype is a visual representation of the
complete set of chromosomes in a cell. Haplotypes are groups of genes within an organism
that was inherited together from a single parent. Genotypes provide the underlying
biological instructions that eventually manifest as physical traits.
7. Which of the following best defines an ‘allele’?
A. A protein that binds to DNA
B. A sugar molecule in the DNA backbone
C. An alternative form of a single gene
D. The entire set of genetic material
Correct Answer: C
Explanation: An allele is one of two or more versions of a DNA sequence at a given
genomic location. Proteins that bind to DNA are typically transcription factors or histones
rather than genes themselves. Deoxyribose is the sugar molecule found in the DNA
backbone, not an allele. The entire set of genetic material in an organism is known as the
genome. Alleles are responsible for the variations in traits seen among individuals of the
same species.
8. What is the primary function of telomeres in a chromosome?
A. Encoding for metabolic enzymes
B. Providing a site for microtubule attachment
C. Protecting the ends of the DNA from degradation
D. Storing excess nitrogenous bases
Correct Answer: C
Explanation: Telomeres are repetitive sequences at the ends of chromosomes that prevent
the loss of genetic information during replication. They do not encode for functional
proteins like metabolic enzymes. The site for microtubule attachment during mitosis is the
kinetochore located at the centromere. Telomeres do not serve as storage units for
nitrogenous bases within the cell. Without telomeres, chromosomes would gradually
shorten and lose essential genes over multiple cell divisions.
and Latest Questions and Correct Answers with
Rationale - Portage Learning
1. Which of the following serves as the basic building block of a DNA molecule?
A. Amino acid
B. Monosaccharide
C. Fatty acid
D. Nucleotide
Correct Answer: D
Explanation: A nucleotide is the fundamental structural unit of DNA consisting of a sugar,
phosphate, and nitrogenous base. Amino acids are the building blocks of proteins rather
than nucleic acids. Fatty acids are components of lipids used for energy storage and
membrane structure. Monosaccharides are simple sugars that serve as the building blocks
for complex carbohydrates. Therefore, the nucleotide is the only option that directly
composes the genetic material DNA.
2. In the DNA double helix, which nitrogenous base pairs with Cytosine?
A. Guanine
B. Thymine
C. Uracil
D. Adenine
Correct Answer: A
Explanation: According to base-pairing rules, Guanine always forms three hydrogen bonds
with Cytosine in DNA. Adenine pairs specifically with Thymine in DNA molecules to
maintain the double helix width. Uracil is a nitrogenous base found only in RNA where it
replaces Thymine. Thymine is a pyrimidine that pairs with the purine Adenine in a
standard DNA structure. Understanding these complementary pairs is essential for
predicting DNA sequences and replication patterns.
3. What is the specific physical location of a gene on a chromosome called?
A. Allele
B. Locus
C. Centromere
D. Telomere
,Correct Answer: B
Explanation: The locus refers to the fixed position on a chromosome where a particular
gene or genetic marker is located. An allele is a variant form of a gene rather than the
physical location itself. The centromere is the constricted region of a chromosome that
joins sister chromatids together. Telomeres are the repetitive DNA sequences located at the
very ends of linear chromosomes. Identifying the locus is a critical step in genetic mapping
and studying inheritance patterns.
4. How many pairs of autosomes are found in a typical human somatic cell?
A. 22
B. 46
C. 23
D. 1
Correct Answer: A
Explanation: Human somatic cells contain a total of 23 pairs of chromosomes, of which 22
pairs are autosomes. The 23rd pair consists of the sex chromosomes which determine the
biological sex of the individual. A total count of 46 individual chromosomes exists in a
diploid human cell. Only one pair of chromosomes serves as the sex-determining pair in
humans. Thus, the correct number of autosomal pairs is 22.
5. Which structure is formed when DNA wraps around histone proteins?
A. Centrosome
B. Ribosome
C. Nucleosome
D. Lysosome
Correct Answer: C
Explanation: A nucleosome is the basic unit of DNA packaging in eukaryotes consisting of
a segment of DNA wound around eight histone proteins. Ribosomes are cellular machines
responsible for protein synthesis rather than DNA storage. Centrosomes are organelles that
serve as the main microtubule-organizing centers during cell division. Lysosomes are
membrane-bound organelles containing digestive enzymes for breaking down waste
materials. The formation of nucleosomes is the first level of folding required to fit DNA into
the nucleus.
6. What term describes the genetic makeup of an organism for a specific trait?
A. Genotype
B. Phenotype
, C. Karyotype
D. Haplotype
Correct Answer: A
Explanation: The genotype represents the specific set of alleles an individual carries for a
particular gene. The phenotype refers to the observable physical or physiological
characteristics resulting from the genotype. A karyotype is a visual representation of the
complete set of chromosomes in a cell. Haplotypes are groups of genes within an organism
that was inherited together from a single parent. Genotypes provide the underlying
biological instructions that eventually manifest as physical traits.
7. Which of the following best defines an ‘allele’?
A. A protein that binds to DNA
B. A sugar molecule in the DNA backbone
C. An alternative form of a single gene
D. The entire set of genetic material
Correct Answer: C
Explanation: An allele is one of two or more versions of a DNA sequence at a given
genomic location. Proteins that bind to DNA are typically transcription factors or histones
rather than genes themselves. Deoxyribose is the sugar molecule found in the DNA
backbone, not an allele. The entire set of genetic material in an organism is known as the
genome. Alleles are responsible for the variations in traits seen among individuals of the
same species.
8. What is the primary function of telomeres in a chromosome?
A. Encoding for metabolic enzymes
B. Providing a site for microtubule attachment
C. Protecting the ends of the DNA from degradation
D. Storing excess nitrogenous bases
Correct Answer: C
Explanation: Telomeres are repetitive sequences at the ends of chromosomes that prevent
the loss of genetic information during replication. They do not encode for functional
proteins like metabolic enzymes. The site for microtubule attachment during mitosis is the
kinetochore located at the centromere. Telomeres do not serve as storage units for
nitrogenous bases within the cell. Without telomeres, chromosomes would gradually
shorten and lose essential genes over multiple cell divisions.
