The question asks which options are statements of the Chromosome Theory of Heredity (also called the Chromosome Theory of Inheritance, developed by Sutton and Boveri).
The correct answers are:
✅ Genes are arranged in chromosomes in linear order at specific loci.
- This is a core statement of the chromosome theory.
✅ Allelic genes are located in identical loci of homologous chromosomes.
- This is another direct statement of the chromosome theory.
✅ Chromosomes are made up of DNA and proteins.
- This describes the molecular composition of chromosomes, which is a foundational part of chromosome theory.
Why the others are NOT statements of the chromosome theory:
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"Each gene carries information about the sequence of amino acids in a particular protein molecule" - This is a statement of the "one gene - one protein" hypothesis (Beadle & Tatum), not chromosome theory.
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"Cytoplasmic heredity is related to hereditary information contained in mitochondrial DNA" - This describes extranuclear/cytoplasmic inheritance, which is actually separate from chromosome theory (chromosome theory deals with nuclear chromosomes).
-
"Eukaryotic cells have a compartmentalized nucleus" - This is a statement about cell structure/biology, not chromosome theory specifically.
**Summary of correct answers: 2nd, 4th, and 6th options.**Pulex irritans is the human flea. Like all fleas (Order Siphonaptera), it undergoes complete metamorphosis (holometabolism).
Correct Answer: ✅ Indirect with complete metamorphosis
Explanation:
Pulex irritans (the human flea) belongs to Order Siphonaptera, which is a holometabolous insect group. Its life cycle has 4 distinct stages:
- Egg - laid in host's environment (bedding, fur, etc.)
- Larva - worm-like, free-living, feeds on organic debris
- Pupa - enclosed in a silk cocoon
- Adult - parasitic, blood-sucking
This is called indirect development because the organism does not resemble the adult at birth/hatching, and undergoes a dramatic transformation (metamorphosis). Since all four stages are present (including a distinct pupal stage), it is complete metamorphosis - not incomplete.
Why the others are wrong:
- Direct development - No metamorphosis at all (e.g., humans, reptiles). Flea larvae look nothing like adults.
- Indirect with incomplete metamorphosis (hemimetabolism) - Only 3 stages: egg → nymph → adult (e.g., cockroaches, grasshoppers). Fleas have a pupal stage, so this doesn't apply.
- Both complete and incomplete / both direct and indirect - Fleas are strictly holometabolous; they don't switch between modes.
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