Extra-Chromosomal Inheritance Practice Questions
20 free Extra-Chromosomal Inheritance practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which type of inheritance is characteristic of mitochondrial DNA transmission?
- A Paternal inheritance
- B Biparental inheritance
- C Autosomal inheritance
- D Maternal inheritance
Correct answer: Maternal inheritance
Mitochondrial DNA is inherited almost exclusively from the mother because the egg contributes most of the cytoplasm. Sperm mitochondria are typically degraded after fertilization.
Which organelle is primarily responsible for extra-chromosomal inheritance in animal cells?
- A Nucleus
- B Golgi apparatus
- C Lysosome
- D Mitochondria
Correct answer: Mitochondria
Mitochondria contain their own DNA separate from nuclear DNA. This DNA is responsible for extra-chromosomal inheritance in animal cells.
Which feature distinguishes mitochondrial DNA from nuclear DNA?
- A Linear structure
- B Histone association
- C Circular structure
- D Located in chromosomes
Correct answer: Circular structure
Mitochondrial DNA is circular and resembles bacterial DNA. It does not associate with histones like nuclear DNA does.
Which condition demonstrates mitochondrial inheritance in humans?
- A Charcot-Marie-Tooth disease type 1A
- B Sickle cell anemia
- C Leber's hereditary optic neuropathy
- D Klinefelter syndrome
Correct answer: Leber's hereditary optic neuropathy
Leber's hereditary optic neuropathy is caused by mutations in mitochondrial DNA. It is inherited maternally and affects vision.
What is the term for the presence of both normal and mutated mitochondrial DNA within a cell?
- A Homoplasmy
- B Polyploidy
- C Uniparental disomy
- D Heteroplasmy
Correct answer: Heteroplasmy
Heteroplasmy refers to the coexistence of normal and mutated mitochondrial DNA within the same cell. This can influence disease severity.
Which process explains the origin of mitochondria and chloroplasts?
- A Gene duplication
- B Mutation theory
- C Endosymbiotic theory
- D Chromosomal theory of inheritance
Correct answer: Endosymbiotic theory
The endosymbiotic theory suggests that mitochondria and chloroplasts originated from free-living bacteria engulfed by ancestral eukaryotic cells. Their own DNA supports this idea.
Chloroplast DNA is primarily inherited through which parent in most plants?
- A Paternal parent
- B Both parents equally
- C Maternal parent
- D Random inheritance
Correct answer: Maternal parent
In most plants, chloroplast DNA is inherited maternally through the egg cell. Pollen typically contributes little cytoplasm.
Which statement best describes cytoplasmic inheritance?
- A Inheritance via organelles outside the nucleus
- B Inheritance via nuclear genes only
- C Inheritance based on epigenetic gene modifications
- D Inheritance via protein synthesis
Correct answer: Inheritance via organelles outside the nucleus
Cytoplasmic inheritance involves genes located outside the nucleus, mainly in mitochondria and chloroplasts. These genes are passed through cytoplasmic components.
Which trait in plants is often associated with chloroplast inheritance?
- A Leaf variegation
- B Flower color
- C Seed size
- D Stem thickness variation
Correct answer: Leaf variegation
Leaf variegation is often controlled by chloroplast genes. Mutations in chloroplast DNA can lead to patches of green and white tissue.
Why is mitochondrial inheritance considered non-Mendelian?
- A It follows dominant-recessive patterns
- B It involves independent assortment
- C It does not follow Mendel's laws
- D It involves crossing over
Correct answer: It does not follow Mendel's laws
Mitochondrial inheritance does not follow Mendel's laws because it is transmitted through cytoplasm rather than nuclear genes. It shows maternal inheritance patterns.
Which of the following is a characteristic of chloroplast DNA?
- A Circular and small
- B Linear and large
- C Double-stranded RNA
- D Protein-based genome
Correct answer: Circular and small
Chloroplast DNA is circular and relatively small, similar to bacterial genomes. It supports the endosymbiotic origin of chloroplasts.
What is the main reason paternal mitochondria are not inherited?
- A They are inactive
- B They lack DNA
- C They are selectively degraded
- D They are diluted out during embryonic development
Correct answer: They are selectively degraded
Paternal mitochondria are actively degraded after fertilization. This ensures maternal inheritance of mitochondrial DNA.
Which organelle is involved in photosynthesis and shows extra-chromosomal inheritance?
- A Chloroplast
- B Mitochondria
- C Endoplasmic reticulum
- D Ribosome
Correct answer: Chloroplast
Chloroplasts are responsible for photosynthesis and contain their own DNA. This DNA is inherited independently of nuclear DNA.
Which term describes identical mitochondrial DNA copies within a cell?
- A Homoplasmy
- B Heteroplasmy
- C Diploidy
- D Polyteny
Correct answer: Homoplasmy
Homoplasmy refers to the presence of identical mitochondrial DNA copies in a cell. This contrasts with heteroplasmy, where variations exist.
Which experimental evidence supports cytoplasmic inheritance?
- A Reciprocal crosses showing different results
- B Punnett square analysis
- C Chromosomal mapping using linkage analysis techniques
- D Protein synthesis experiments
Correct answer: Reciprocal crosses showing different results
Reciprocal crosses showing different outcomes indicate cytoplasmic inheritance. This suggests that traits are inherited through cytoplasmic components rather than nuclear genes.
Which genome is smaller and encodes fewer proteins compared to nuclear DNA?
- A Mitochondrial genome
- B Nuclear genome
- C Plasmid genome
- D Bacteriophage genome
Correct answer: Mitochondrial genome
The mitochondrial genome is much smaller than the nuclear genome and encodes only a limited number of proteins. Most mitochondrial proteins are encoded by nuclear genes.
Which inheritance pattern is shown when only offspring of affected mothers are affected?
- A Autosomal dominant
- B X-linked
- C Mitochondrial
- D Y-linked
Correct answer: Mitochondrial
Mitochondrial inheritance shows this pattern because mitochondria are transmitted from mothers. Affected fathers do not pass the trait to offspring.
Which structure contains genes responsible for ATP production in cells?
- A Nucleus
- B Mitochondria
- C Chloroplast
- D Golgi apparatus
Correct answer: Mitochondria
Mitochondria contain genes that code for proteins involved in oxidative phosphorylation and ATP production. These genes are part of mitochondrial DNA.
Which concept explains why chloroplasts divide independently of the nucleus?
- A Linked gene inheritance
- B Autonomous replication
- C Chromosomal crossing over
- D Elevated mutation rate
Correct answer: Autonomous replication
Chloroplasts replicate autonomously using their own DNA. This autonomy supports their role in extra-chromosomal inheritance.
Which of the following best describes the genetic origin of chloroplasts?
- A Derived from mitochondria
- B Derived from cyanobacteria
- C Derived from the nucleus
- D Derived from RNA viruses
Correct answer: Derived from cyanobacteria
Chloroplasts are believed to have evolved from cyanobacteria through endosymbiosis. Their DNA and structure resemble those of these bacteria.