Chapter 3 — Reproduction in Living Organisms · Biology. These are 10 questions from the Magmo3 bank on this lesson, from easy to hard. Solve each one, then open "Show answer and explanation". Magmo3 has 35 questions on this lesson, each with an explanation.
The type of division by which gametes are formed is...
Correct answer: (D) Meiosis (reduction division)
Explanation: Gametes are formed by meiosis (reduction division), which halves the number of chromosomes so that the gametes are haploid.
In fish and amphibians, fertilization is...
Correct answer: (D) External, in water
Explanation: Fish and amphibians release their gametes into the water and fertilization takes place outside the body (external fertilization).
The male gamete in animals is the...
Correct answer: (B) Sperm
Explanation: The male gamete is the sperm, which is small, motile, and has a tail, while the female gamete is the egg.
The formation of male bees from unfertilized eggs is an example of...
Correct answer: (B) Parthenogenesis
Explanation: Parthenogenesis is the growth of an egg into a new individual without fertilization; in bees, unfertilized eggs grow into haploid males.
In meiosis I, separation occurs for the...
Correct answer: (A) Homologous chromosomes
Explanation: In meiosis I (the reduction division) the homologous chromosomes separate from each other, whereas the sister chromatids separate in meiosis II.
Meiosis consists of...
Correct answer: (B) Two successive divisions
Explanation: Meiosis takes place over two successive divisions (meiosis I, the reduction division, and meiosis II), producing 4 haploid cells.
A hermaphrodite organism is one that...
Correct answer: (B) Bears both male and female reproductive organs in the same individual
Explanation: A hermaphrodite organism (such as the earthworm) bears both male and female organs in the same individual, but cross-fertilization between two individuals usually takes place.
The zygote formed by fertilization is diploid (2n) because it...
Correct answer: (D) Combined one set of chromosomes from each haploid gamete (n plus n)
Explanation: Each gamete is haploid (n), and the union of the two gametes combines two sets (n from the father and n from the mother), making the zygote diploid (2n).
The DNA content of a cell is measured during meiosis: it starts at 10 units, rises to 20 units, falls to 10 units, and finally falls to 5 units. Which events cause the two falls, in order?
Correct answer: (A) The separation of homologous chromosomes, then the separation of sister chromatids
Explanation: The rise from 10 to 20 is DNA replication before meiosis. The first fall (20 → 10) happens at the end of meiosis I, when homologous chromosomes go to separate cells, and the second fall (10 → 5) happens at the end of meiosis II, when sister chromatids go to separate cells.
Why does sexual reproduction give a species a greater chance of survival when the environment changes?
Correct answer: (A) Because genetic diversity increases the chance of having adapted individuals
Explanation: The genetic diversity resulting from sexual reproduction means there are individuals with different traits, so if the environment changes some of them may be able to adapt and survive.
The first 10 questions in every subject are free, each with an explanation.