BSC Final Exam questions and answers 2025-2026
update
What is asexual reproduction? - ✔✔ANS A type of reproduction that does not involve the fusion of gamete
(sex cells) and results in offspring that are genetically identical to the single parent
What is sexual reproduction? - ✔✔ANS A biological process where offspring are produced by the fusio
of gametes (reproductive cells) from two parents, resulting in offspring with a unique combination o
genetic material
How are asexual and sexual reproduction similar? (5 reasons) - ✔✔ANS 1. Purpose: Both result in th
production of new organisms, allowing for the continuation of a species.
2. Genetic Material: Both involve the transmission of DNA from parent(s) to offspring.
3. Cell Division: Both rely on cell division processes (like mitosis in asexual reproduction, and meiosi
followed by fertilization in sexual reproduction).
4. Growth and Development: In both cases, the resulting offspring grow and develop from a single cell.
5. Use of Energy: Both processes require energy and resources from the organism.
How are asexual and sexual reproduction different? (5 differences) - ✔✔ANS 1. Number of Parents
Asexual Reproduction: Involves only one parent.
Sexual Reproduction: Involves two parents (male and female gametes).
2. Genetic Variation
Asexual: Offspring are genetically identical to the parent (clones).
Sexual: Offspring have genetic variation due to the combination of DNA from both parents.
3. Reproductive Process
Asexual: Typically involves mitosis (e.g., binary fission, budding).
Sexual: Involves meiosis to produce gametes, followed by fertilization.
4. Speed and Efficiency
Asexual: Usually faster and requires less energy.
Sexual: Slower and more energy-intensive, but increases adaptability.
5. Examples
Asexual: Bacteria (binary fission), hydra (budding), some plants (runners).
,Sexual: Most animals, humans, and many plants.
Ploidy definition - ✔✔ANS Ploidy refers to the number of complete sets of chromosomes in a cell.
Haploid definition - ✔✔ANS Haploid refers to a cell that contains one complete set of chromosome
(denoted as n).
Diploid definition - ✔✔ANS Diploid refers to a cell that contains two complete sets of chromosomes—on
set inherited from each parent. It is denoted as 2n.
Chromosomes definition - ✔✔ANS Chromosomes are long, thread-like structures made of DNA an
proteins (mainly histones) that carry genetic information.
Chromatid definition - ✔✔ANS A chromatid is one of two identical halves of a duplicated chromosome.
Homologous chromosomes definition - ✔✔ANS Homologous chromosomes are pairs of chromosomes i
a diploid organism that:
Have the same length, shape, and centromere position
Carry the same types of genes in the same order, but not necessarily the same alleles (versions of a gene
One comes from the mother (maternal chromosome) and one from the father (paternal chromosome)
What are the 4 phases of the eukaryotic cell cycle? - ✔✔ANS 1. G1 phase
2. S phase
3. G2 phase
4. M phase
What happens during G1 phase? - ✔✔ANS G1 phase:
Cell grows and performs normal functions
Prepares for DNA replication
G1 checkpoint ensures conditions are right to proceed
What is the G1 checkpoint? - ✔✔ANS G1 checkpoint:
Checks for cell size, nutrients, and DNA damage
Ensures conditions are favorable for DNA replication
Decides if the cell will enter S phase or pause (or go to G0)
What happens during S phase? - ✔✔ANS S phase:
,DNA is replicated
Each chromosome forms two sister chromatids
DNA content doubles
What happens during S checkpoint? - ✔✔ANS Monitors DNA replication accuracy
Detects and repairs any DNA damage during replication
Ensures DNA synthesis is complete before proceeding to G2 phase
What happens during G2 phase? - ✔✔ANS Cell continues to grow
Final preparations for mitosis
Repairs DNA replication errors
Produces proteins needed for cell division
G2 checkpoint ensures DNA is fully replicated and undamaged before mitosis begins
What happens during G2 checkpoint? - ✔✔ANS Checks for complete and accurate DNA replication
Detects DNA damage and repairs it
Confirms cell size and readiness for mitosis
Prevents entry into mitosis if problems are detected
What happens during M phase? - ✔✔ANS Mitosis: division of the nucleus into two identical nuclei
Cytokinesis: division of the cytoplasm, forming two daughter cells
Ensures equal distribution of chromosomes to each daughter cell
What happens during M checkpoint? - ✔✔ANS Ensures all chromosomes are properly attached to th
spindle fibers
Confirms chromosomes are aligned at the metaphase plate
Prevents progression to anaphase until all chromosomes are correctly positioned to avoid errors i
chromosome separation
What triggers the G1 checkpoint? - ✔✔ANS Cell size (must be large enough)
Nutrient availability (sufficient resources)
Growth factors (external signals)
DNA integrity (no damage detected)
What triggers the S checkpoint? - ✔✔ANS Detection of errors or damage during DNA replication
Incomplete DNA synthesis
Activation of repair mechanisms if problems are found
, What triggers the G2 checkpoint? - ✔✔ANS Incomplete DNA replication
DNA damage or errors detected after replication
Insufficient cell size or resources
If problems are found, the cell cycle is paused to allow repair or growth before entering mitosis.
What triggers the M checkpoint? - ✔✔ANS Improper attachment of chromosomes to spindle fibers
Misalignment of chromosomes at the metaphase plate
It prevents the cell from progressing to anaphase until all chromosomes are correctly attached an
aligned, ensuring accurate chromosome segregation.
What is the function of mitosis? - ✔✔ANS To produce two genetically identical diploid daughter cells fo
growth, repair, and asexual reproduction by dividing the nucleus of a eukaryotic cell.
What are the phases if mitosis? - ✔✔ANS 1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
5. Cytokinesis
What happens during prophase? - ✔✔ANS Chromosomes condense and become visible.
Spindle fibers begin to form from centrosomes.
Nuclear envelope starts to break down.
Centrosomes move to opposite poles of the cell.
What happens during metaphase? - ✔✔ANS Chromosomes line up at the metaphase plate (middle of th
cell).
Spindle fibers attach to the centromeres of each chromosome via the kinetochores.
Cell checks that all chromosomes are properly attached to the spindle.
What happens during anaphase? - ✔✔ANS Sister chromatids are pulled apart toward opposite poles o
the cell.
The centromeres split, allowing each chromatid to become an individual chromosome.
Spindle fibers shorten to move chromatids.
What happens during telophase? - ✔✔ANS Chromosomes arrive at opposite poles of the cell.
Nuclear envelopes re-form around each set of chromosomes.
update
What is asexual reproduction? - ✔✔ANS A type of reproduction that does not involve the fusion of gamete
(sex cells) and results in offspring that are genetically identical to the single parent
What is sexual reproduction? - ✔✔ANS A biological process where offspring are produced by the fusio
of gametes (reproductive cells) from two parents, resulting in offspring with a unique combination o
genetic material
How are asexual and sexual reproduction similar? (5 reasons) - ✔✔ANS 1. Purpose: Both result in th
production of new organisms, allowing for the continuation of a species.
2. Genetic Material: Both involve the transmission of DNA from parent(s) to offspring.
3. Cell Division: Both rely on cell division processes (like mitosis in asexual reproduction, and meiosi
followed by fertilization in sexual reproduction).
4. Growth and Development: In both cases, the resulting offspring grow and develop from a single cell.
5. Use of Energy: Both processes require energy and resources from the organism.
How are asexual and sexual reproduction different? (5 differences) - ✔✔ANS 1. Number of Parents
Asexual Reproduction: Involves only one parent.
Sexual Reproduction: Involves two parents (male and female gametes).
2. Genetic Variation
Asexual: Offspring are genetically identical to the parent (clones).
Sexual: Offspring have genetic variation due to the combination of DNA from both parents.
3. Reproductive Process
Asexual: Typically involves mitosis (e.g., binary fission, budding).
Sexual: Involves meiosis to produce gametes, followed by fertilization.
4. Speed and Efficiency
Asexual: Usually faster and requires less energy.
Sexual: Slower and more energy-intensive, but increases adaptability.
5. Examples
Asexual: Bacteria (binary fission), hydra (budding), some plants (runners).
,Sexual: Most animals, humans, and many plants.
Ploidy definition - ✔✔ANS Ploidy refers to the number of complete sets of chromosomes in a cell.
Haploid definition - ✔✔ANS Haploid refers to a cell that contains one complete set of chromosome
(denoted as n).
Diploid definition - ✔✔ANS Diploid refers to a cell that contains two complete sets of chromosomes—on
set inherited from each parent. It is denoted as 2n.
Chromosomes definition - ✔✔ANS Chromosomes are long, thread-like structures made of DNA an
proteins (mainly histones) that carry genetic information.
Chromatid definition - ✔✔ANS A chromatid is one of two identical halves of a duplicated chromosome.
Homologous chromosomes definition - ✔✔ANS Homologous chromosomes are pairs of chromosomes i
a diploid organism that:
Have the same length, shape, and centromere position
Carry the same types of genes in the same order, but not necessarily the same alleles (versions of a gene
One comes from the mother (maternal chromosome) and one from the father (paternal chromosome)
What are the 4 phases of the eukaryotic cell cycle? - ✔✔ANS 1. G1 phase
2. S phase
3. G2 phase
4. M phase
What happens during G1 phase? - ✔✔ANS G1 phase:
Cell grows and performs normal functions
Prepares for DNA replication
G1 checkpoint ensures conditions are right to proceed
What is the G1 checkpoint? - ✔✔ANS G1 checkpoint:
Checks for cell size, nutrients, and DNA damage
Ensures conditions are favorable for DNA replication
Decides if the cell will enter S phase or pause (or go to G0)
What happens during S phase? - ✔✔ANS S phase:
,DNA is replicated
Each chromosome forms two sister chromatids
DNA content doubles
What happens during S checkpoint? - ✔✔ANS Monitors DNA replication accuracy
Detects and repairs any DNA damage during replication
Ensures DNA synthesis is complete before proceeding to G2 phase
What happens during G2 phase? - ✔✔ANS Cell continues to grow
Final preparations for mitosis
Repairs DNA replication errors
Produces proteins needed for cell division
G2 checkpoint ensures DNA is fully replicated and undamaged before mitosis begins
What happens during G2 checkpoint? - ✔✔ANS Checks for complete and accurate DNA replication
Detects DNA damage and repairs it
Confirms cell size and readiness for mitosis
Prevents entry into mitosis if problems are detected
What happens during M phase? - ✔✔ANS Mitosis: division of the nucleus into two identical nuclei
Cytokinesis: division of the cytoplasm, forming two daughter cells
Ensures equal distribution of chromosomes to each daughter cell
What happens during M checkpoint? - ✔✔ANS Ensures all chromosomes are properly attached to th
spindle fibers
Confirms chromosomes are aligned at the metaphase plate
Prevents progression to anaphase until all chromosomes are correctly positioned to avoid errors i
chromosome separation
What triggers the G1 checkpoint? - ✔✔ANS Cell size (must be large enough)
Nutrient availability (sufficient resources)
Growth factors (external signals)
DNA integrity (no damage detected)
What triggers the S checkpoint? - ✔✔ANS Detection of errors or damage during DNA replication
Incomplete DNA synthesis
Activation of repair mechanisms if problems are found
, What triggers the G2 checkpoint? - ✔✔ANS Incomplete DNA replication
DNA damage or errors detected after replication
Insufficient cell size or resources
If problems are found, the cell cycle is paused to allow repair or growth before entering mitosis.
What triggers the M checkpoint? - ✔✔ANS Improper attachment of chromosomes to spindle fibers
Misalignment of chromosomes at the metaphase plate
It prevents the cell from progressing to anaphase until all chromosomes are correctly attached an
aligned, ensuring accurate chromosome segregation.
What is the function of mitosis? - ✔✔ANS To produce two genetically identical diploid daughter cells fo
growth, repair, and asexual reproduction by dividing the nucleus of a eukaryotic cell.
What are the phases if mitosis? - ✔✔ANS 1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
5. Cytokinesis
What happens during prophase? - ✔✔ANS Chromosomes condense and become visible.
Spindle fibers begin to form from centrosomes.
Nuclear envelope starts to break down.
Centrosomes move to opposite poles of the cell.
What happens during metaphase? - ✔✔ANS Chromosomes line up at the metaphase plate (middle of th
cell).
Spindle fibers attach to the centromeres of each chromosome via the kinetochores.
Cell checks that all chromosomes are properly attached to the spindle.
What happens during anaphase? - ✔✔ANS Sister chromatids are pulled apart toward opposite poles o
the cell.
The centromeres split, allowing each chromatid to become an individual chromosome.
Spindle fibers shorten to move chromatids.
What happens during telophase? - ✔✔ANS Chromosomes arrive at opposite poles of the cell.
Nuclear envelopes re-form around each set of chromosomes.
