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Question 1: What does the acronym DNA stand for?
- Deoxyribonucleic acid
- Deoxyribose nitrogenous acid
- Dynamic nucleic acid
- Double nucleic acid
Answer: A. Deoxyribonucleic acid
Explanation: DNA stands for deoxyribonucleic acid. It is the molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms.
Question 2: What is the characteristic shape of a DNA molecule?
- Flat sheet
- Double helix
- Single loop
- Triple sphere
Answer: B. Double helix
Explanation: The DNA molecule has a double helix structure, which is often described as looking like a twisting ladder or a spiral staircase.
Question 3: Which of these is one of the four nitrogen bases in DNA?
- Protein
- Uracil
- Adenine
- Chromosome
Answer: C. Adenine
Explanation: The four nitrogen bases that make up DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). Uracil is found in RNA instead.
Question 4: What are specific sections of DNA that contain instructions for making proteins called?
- Genes
- Phenotypes
- Chromosomes
- Alleles
Answer: A. Genes
Explanation: Genes are specific segments of DNA that serve as the basic unit of heredity and contain the instructions for building proteins in the body.
Question 5: How many chromosomes do humans typically have in their cells?
- 48
- 46
- 20,000
- 23
Answer: B. 46
Explanation: Humans have 46 chromosomes in total, which are arranged in 23 pairs. One set of 23 chromosomes is inherited from each biological parent.
Question 6: What term describes different versions of the same gene?
- Alleles
- Proteins
- Traits
- Genomes
Answer: A. Alleles
Explanation: Alleles are different versions of the same gene. For example, one allele might code for blue eye color while another codes for brown eye color.
Question 7: Which type of allele is expressed even if only one copy is present?
- Recessive
- Hidden
- Neutral
- Dominant
Answer: D. Dominant
Explanation: A dominant allele is expressed in the phenotype even if the individual only has one copy of that specific allele in their genetic makeup.
Question 8: What is the term for the visible characteristics of an organism resulting from its genes?
- Phenotype
- Chromosome
- Allele
- Genotype
Answer: A. Phenotype
Explanation: The phenotype refers to the observable physical or biochemical characteristics of an organism, such as eye color or height, determined by both genetics and environment.
Question 9: Approximately how many genes are in the human genome?
- 1,000 to 5,000
- 1 million
- 20,000 to 25,000
- 100,000 to 150,000
Answer: C. 20,000 to 25,000
Explanation: Scientific research estimates that the human genome contains approximately 20,000 to 25,000 genes, which provide the blueprint for human biological functions.
Question 10: Under what condition is a recessive allele expressed?
- When it is the only allele present
- When a dominant allele is also present
- It is always expressed
- When two copies are present
Answer: D. When two copies are present
Explanation: A recessive allele is only expressed in the phenotype if an individual has two copies of that allele and no dominant allele is present to mask it.