Biology Grade 10 Practice Questions - Unit 7: Cell Division and Reproduction
Mitosis Stages
Correct sequence of stages in mitosis: C. Prophase, metaphase, anaphase, telophase
Prophase Events in Animal Cells
Structures that disappear during prophase in an animal cell: B. nucleus and nucleolus
Structures formed during prophase in an animal cell: D. spindle fibres
Crossing Over
Crossing over first takes place during: C. prophase I
DNA Content During Cell Cycle
DNA replication takes place during: B. stage II
Cell Cycle
Roles of the cell cycle:
Growth and development
Repair of tissues
Asexual reproduction
Mitotic Index
Mitotic index formula:
Anaphase Time Calculation
Calculating time spent in anaphase:
Time in anaphase = (Number of cells in anaphase / Total number of cells) x Total cell cycle time
Convert total cell cycle time to minutes.
Meiosis and Genetic Variation
Diagram completion: Show chromosomes after crossing over with exchanged segments.
Advantage of crossing over:
Increases genetic variation by creating new combinations of alleles on chromosomes.
Contributes to the uniqueness of gametes.
Increases the adaptability of a population to changing environments.
Root Tip Squash for Mitosis Observation
Why the tip of the onion root is used:
The tip is the area of active cell division (meristem).
Why acid is used:
To break down the cell walls and separate the cells.
Suitable stain for root tip squash:
Examples: Toluidine blue, acetic orcein, Giemsa stain
Sperm Cell and Egg
Sperm cell structures:
example Head (containing the acrosome and nucleus)
Midpiece (containing mitochondria)
Tail (flagellum)
Egg structures:
example Nucleus
Cytoplasm
Zona pellucida
Corona radiata
Fertilization
*Site of sperm production: Testes
*Site of fertilisation: Fallopian tube
*Enzyme released from acrosome: Acrosin
*Provides nutrition to the embryo: Endosperm
Events after sperm entry into the egg:
Cortical reaction: Release of cortical granules that harden the zona pellucida, preventing polyspermy.
Activation of the egg: Triggering of metabolic processes and the completion of meiosis.
Acrosin release from the acrosome:
Exocytosis: The acrosomal membrane fuses with the sperm cell membrane, releasing acrosin.
Triggered by contact with the zona pellucida.
Flowering Plant Reproduction
Ovule structures:
Embryo sac
Egg cell
Polar nuclei
Antipodal cells
Pollen tube structures:
Tube nucleus
Sperm nuclei
DNA content differences in embryo and endosperm cells:
Embryo cell is diploid (2n): Formed from the fusion of one sperm (n) and one egg (n).
Endosperm cell is triploid (3n): Formed from the fusion of one sperm (n) and two polar nuclei (2n).
Different quantities of DNA reflect their different origins and roles in the plant life cycle.
question examples !
Here are some multiple-choice and essay questions related to the topics you've specified for your upcoming test on Monday, May 19, 2025:
Mitosis
Multiple Choice:
Which of the following is the correct sequence of stages in mitosis?
A. Anaphase, metaphase, prophase, telophase
B. Metaphase, prophase, telophase, anaphase
C. Prophase, metaphase, anaphase, telophase
D. Telophase, anaphase, metaphase, prophase
During which phase of mitosis do the sister chromatids separate?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
What is the role of mitosis in multicellular organisms?
A. Sexual reproduction
B. Production of gametes
C. Growth and repair of tissues
D. Genetic variation
Essay:
Describe the stages of mitosis. What is the importance of mitosis in living organisms? Explain the concept of mitotic index and its significance.
Meiosis
Multiple Choice:
Crossing over occurs during which phase of meiosis?
A. Prophase II
B. Metaphase I
C. Prophase I
D. Metaphase II
What is the outcome of meiosis?
A. Two diploid cells
B. Four diploid cells
C. Two haploid cells
D. Four haploid cells
What is the importance of independent assortment in meiosis?
A. It ensures identical daughter cells.
B. It increases genetic variation.
C. It reduces the chromosome number.
D. It repairs damaged DNA.
Essay:
Describe the process of meiosis, highlighting the key differences between meiosis I and meiosis II. How do crossing over and independent assortment contribute to genetic variation?
DNA Content During Cell Cycle
Multiple Choice:
During which stage of the cell cycle does DNA replication occur?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
If a cell has 40 picograms of DNA in the G1 phase, how much DNA will it have in the G2 phase?
A. 10 picograms
B. 20 picograms
C. 40 picograms
D. 80 picograms
Essay:
Explain how DNA content varies during mitosis and meiosis. Draw and label a graph illustrating DNA content changes throughout the cell cycle, including both mitosis and meiosis.
Gametes
Multiple Choice:
Which structure contains mitochondria and provides energy for sperm movement?
A. Head
B. Midpiece
C. Tail
D. Acrosome
Which of the following correctly describes the DNA content of an endosperm cell in a flowering plant?
A. n
B. 2n
C. 3n
D. 4n
Essay:
Compare and contrast the structures and functions of mammalian and plant gametes. Describe the process of gametogenesis in animals.
Reproduction of Mammals
Multiple Choice:
What is the function of the acrosome?
A. To provide energy for sperm movement
B. To protect the sperm nucleus
C. To release enzymes that penetrate the egg
D. To propel the sperm
What is the cortical reaction?
A. A process that attracts sperm to the egg
B. A block to polyspermy
C. The fusion of sperm and egg nuclei
D. The division of the zygote
Essay:
Describe the acrosome reaction and cortical reaction. What are the functions of these reactions in mammalian fertilization?
Reproduction of Plants
Multiple Choice:
Which part of the flower develops into the fruit?
A. Ovule
B. Ovary
C. Stamen
D. Petal
What is the first step in seed germination?
A. Root emergence
B. Shoot emergence
C. Water absorption
D. Photosynthesis
Essay:
Describe the structure of a flower, labeling its key parts. Explain the process of seed germination, including the factors that influence it.