Question

the endosymbiotic hypothesis is a concept that explains _____.
○ why mitochondria and chloroplasts are so unlike each other
○ how eukaryotic cells might have evolved mitochondria and chloroplasts within their cells
○ why chromosomes are only found inside the nucleus of a eukaryotic cell
○ why ribosomes are only found in the eukaryotic cytoplasm, never inside an organelle
○ how plant cells produce usable cellular energy from sunlight

Explanation:

The endosymbiotic hypothesis (or theory) proposes that eukaryotic cells evolved by engulfing prokaryotic cells, which then became mitochondria (from proteobacteria) and chloroplasts (from cyanobacteria) through a symbiotic relationship. Let's analyze each option:

• Option 1: The hypothesis doesn't explain why mitochondria and chloroplasts are unlike each other; it focuses on their origin. Eliminate.
• Option 2: This matches the endosymbiotic hypothesis, as it explains the evolution of mitochondria and chloroplasts within eukaryotic cells.
• Option 3: The hypothesis is about organelle origin, not chromosome location. Eliminate.
• Option 4: Ribosomes are found in organelles like mitochondria and chloroplasts, and the hypothesis doesn't address ribosome location. Eliminate.
• Option 5: Photosynthesis (how plant cells use sunlight for energy) is not explained by the endosymbiotic hypothesis; it's about organelle evolution. Eliminate.

Answer:

B. how eukaryotic cells might have evolved mitochondria and chloroplasts within their cells