Question

question 24
with the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because of

1. unequal division during cytokinesis.
2. dna replication during interphase
3. independent assortment and crossing over during meiosis
4. crossing over during mitosis

Explanation:

• Option 1: Unequal division during cytokinesis mainly affects cell size and organelle distribution, not genetic variation among siblings.
• Option 2: DNA replication during interphase ensures that each daughter cell gets a complete set of DNA. It is a necessary process for cell division but does not create genetic variation among siblings.
• Option 3: Independent assortment (during metaphase I of meiosis) means that homologous chromosomes assort independently of one another. Crossing - over (during prophase I of meiosis) exchanges genetic material between homologous chromosomes. These two processes in meiosis create genetic variation in gametes. When gametes from two parents combine (fertilization), the offspring (siblings, except identical twins) have different genetic combinations, leading to similarity but not identity.
• Option 4: Mitosis is for growth, repair, and asexual reproduction in some organisms. Crossing - over does not occur in mitosis (it occurs in meiosis), and mitosis produces genetically identical daughter cells (in terms of nuclear DNA) in a single - celled organism or for tissue repair in multicellular organisms. It is not related to genetic variation among siblings.

Answer:

1. independent assortment and crossing over during meiosis