All Free Biology MCQs with Answers
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19844 questions · page 740 of 1985
7391. Locus is defined as:
- A. Position of a gene on the chromosome.
- B. Appearance of a trait in an individual
- C. Partner of a gene pair
- D. Gene in an individual for a trait
Explanation: A locus is the specific physical location of a gene or other DNA In genetics, a locus (plural: loci) refers to the specific position or location of a gene or DNA sequence on a chromosome. It is like an address that identifies the position of a particular gene within the genome.
Correct answer: Position of a gene on the chromosome.7392. Chromosomes present in the nucleus have _ function in the cell.
- A. Hereditary
- B. Secretory
- C. Power house
- D. Food synthesis
- E. Protein formation
Explanation: Chromosomes are thread-like structures made up of DNA and proteins, and are present in the nucleus of eukaryotic cells. They carry genetic information in the form of genes that are responsible for the transmission of hereditary traits from one generation to another. Therefore, chromosomes have a critical function in the cell as they play a major role in the inheritance of traits.
Correct answer: Hereditary7393. Which of the following is a physical relationship of genes present on the same chromosomes?
- A. Epistasis
- B. Gene linkage
- C. Crossing over
- D. Pleiotropy
- E. Bombay Phenotype
Explanation: Gene linkage is a physical relationship of genes present on the same chromosome, which results in the tendency of the genes to be inherited together. The closer the genes are on the chromosome, the less likely they are to be separated during crossing over, and the more likely they are to be inherited together.
Correct answer: Gene linkage7394. Failure of separation of sister chromatids is called:
- A. Non-fusion
- B. Non-disjunction
- C. Fusion
- D. Interference
Explanation: Non-disjunction: It is the failure of the chromosomes to separate, which produces daughter cells of an abnormal number of chromosomes. Non-disjunction: It is the failure of the chromosomes to separate, which produces daughter cells of an abnormal number of chromosomes.This may result in several diseases. Nondisjunction, during mitosis, results in the occurrence of cancer, and non-disjunction, during meiosis, may result in Turner, Kleinfelter, or Down Syndrome.meiosis, may result in Turner, Kleinfelter, or Down Syndrome.
Correct answer: Non-disjunction7395. Site of translation is:
- A. Nucleus
- B. Nucleolus
- C. Cytoplasm
- D. Ribosomes
Explanation: Translation is the process of protein synthesis in which the ribosomes read the messenger RNA (mRNA) and use the information to synthesize a protein.
Correct answer: Ribosomes7396. Stop codon signals the end of translation by binding to _.
- A. Release factors
- B. Methionine
- C. tRNA
- D. Amino acids
Explanation: Stop codons are sequences of nucleotides in the mRNA that signal the end of the protein-coding sequence. Release factors are proteins that bind to the stop codon and terminate translation.
Correct answer: Release factors7397. Sequence of stop codon in RNA is:
- A. TAG
- B. AUG
- C. UAG
- D. AAA
- E. AGT
Explanation: UAG is one of the three stop codons, also known as termination codons, in the genetic code. The other two stop codons are UAA and UGA. Stop codons signal the end of protein synthesis during translation. When a stop codon is encountered by the ribosome during translation, it does not code for any amino acid, They are also known as nonsense codons or termination codons because it signals the release of the newly synthesized polypeptide chain from the ribosome. This process ensures that the protein is properly terminated and functional.
Correct answer: UAG7398. _ syndrome is often not recognized until adolescence
- A. Down
- B. Turner
- C. Klinefelter
- D. None of the above
Explanation: Turner syndrome is often not recognized until adolescence. Down syndrome and Klinefelter syndrome are typically recognized at birth. Turner syndrome is a genetic disorder that occurs in females when they have one X chromosome instead of the usual two. This can cause a variety of symptoms, including short stature, delayed puberty, and infertility. In some cases, Turner syndrome may not be diagnosed until adolescence or even adulthood.
Correct answer: Turner7399. The haploid number of chromosomes in human beings:
- A. 4
- B. 10
- C. 24
- D. 23
Explanation: Humans contain 46 chromosomes in their cells, this number is diploid. The haploid number is half of the diploid number which is 23.
Correct answer: 237400. The diagrams below show the results of two types of gene mutation.Which one of the following shows the types of gene mutation producing mutant sequences 1 and 2?
- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: A deletion, as related to genomics, is a type of mutation that involves the loss of one or more nucleotides from a segment of DNA An insertion, as related to genomics, is a type of mutation that involves the addition of one or more nucleotides into a segment of DNA. A substitution mutation is a type of replication error during DNA replication which places the wrong nucleotide or sequence of nucleotides
Correct answer: Option C