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3.2 Cleavage Patterns — Test 1
Q1. Cleavage is best described as:✓ A rapid series of cell divisions with little growth, dividing the zygote into many cells
Q2. If an embryo undergoes 13 cleavage divisions, its overall size compared with the zygote:✓ Remains almost the same
Q3. Holoblastic cleavage means that:✓ The cleavage furrow passes completely through the egg
Q4. Meroblastic cleavage means that:✓ Only part of the egg (the yolk-free cytoplasm) divides
Q5. Mammals show which type of cleavage?✓ Holoblastic rotational
Q6. An amphibian zygote (mesolecithal) undergoes:✓ Holoblastic radial cleavage (unequal)
Q7. Centrolecithal eggs (insects) show which cleavage?✓ Superficial cleavage
Q8. Birds and reptiles (telolecithal eggs) show which cleavage?✓ Meroblastic discoidal cleavage
Q9. Spiral cleavage, with blastomeres set at an angle to the axis, is characteristic of:✓ Molluscs and annelids (protostomes)
Q10. Radial cleavage, with blastomeres directly above one another, is typical of:✓ Echinoderms and chordates (deuterostomes)
Q11. The cleavage pattern of a species is determined mainly by:✓ The amount and distribution of yolk, plus cytoplasmic factors affecting the spindle
Q12. The cleavage in a flatworm (a spiralian) is:✓ Holoblastic spiral
3.2 Cleavage Patterns — Test 2
Q13. Tunicate eggs show which cleavage pattern?✓ Holoblastic bilateral
Q14. Discoidal cleavage refers to:✓ Meroblastic cleavage forming a disc of cells on top of the yolk
Q15. Isolecithal eggs (little yolk) cleave:✓ Holoblastically
Q16. Determinate (mosaic) cleavage means that:✓ Each blastomere's fate is fixed early; isolating one gives a partial embryo
Q17. Indeterminate (regulative) cleavage means that:✓ An isolated early blastomere can still form a complete embryo
Q18. The blastomeres produced by cleavage become progressively:✓ Smaller, because the cytoplasm is partitioned without growth
Q19. In frog cleavage, the vegetal blastomeres are larger than the animal ones because:✓ The yolk-laden vegetal pole divides more slowly
Q20. The first cleavage division in many animals passes through the:✓ Animal–vegetal axis (meridionally)
Q21. Rotational cleavage in mammals is unusual because:✓ The two blastomeres cleave along different (perpendicular) planes
Q22. Superficial cleavage in insects produces, at first, a:✓ Syncytial blastoderm (many nuclei sharing one cytoplasm)
Q23. A fish such as the zebrafish (telolecithal egg) shows which cleavage?✓ Meroblastic discoidal cleavage on top of the yolk