Class 12 Biology Chapter 21 Notes

• Important biology class 12 chapter 21 mcqs for Intermediate part-II students.
• What is Klinefelter’s syndrome?
• What is metastasis?
• What is the importance of bivalent formation?
• What happens during metaphase I?
• What are mutagens? Give one example.
• Important  chapter 21 biology class 12 short questions for Intermediate part-II students.
• What are the apparent symptoms or effects of Down’s syndrome?  OR  What is Down’s syndrome? OR Describe causes and symptoms of Down’s syndrome. OR Write symptoms of Down’s syndrome.
• What are the symptoms of Turner’s syndrome? OR  How Turner’s syndrome is caused and give its features. OR  What is Turner’s syndrome? 
• What is Apoptosis? OR Differentiate between Necrosis and Apoptosis. OR How cell death (Apoptosis) is beneficial for organisms?
• Important chapter 21 biology class 12 important questions for Intermediate part-II students.
• What is mitotic apparatus? OR What is mitotic apparatus? Give its functions. OR  Describe mitotic apparatus. 
• Define cell cycle. OR  Sketch and label cell cycle.
• Define non-disjunction. OR What is non-disjunction or meiotic errors?  OR  What do you mean by non-disjunction? OR What is meant by non-disjunction? Write its consequences.
• Define karyokinesis and cytokinesis. OR  How do karyokinesis and cytokinesis phases of cell division differ?
• Important class 12 biology chapter 21 important long questions and answers for Intermediate part-II students.
• Define meiosis and mitosis.
• What is the importance of mitosis and meiosis? OR Give two main importance of meiosis. 
• Differentiate between benign and malignant tumor.
• Differentiate between Go-phase and S-phase of interphase. OR Describe changes occur during G1-phase.
• Give events of Zygotene.
• Important class 12 biology chapter 21 review answers for Intermediate part-II students.
• How can you identify Cancer cells? OR Cancer is uncontrolled cell division, explain. OR  What are cancer cells? How cancer cells can be distinguished from normal cells? OR  Write any two differences between normal cells and cancer cells.
• In what respects does mitosis in plant cells differ from that in animal cells? OR Explain cytokinesis in plants. OR How cytokinesis occurs in plants?
• How meiosis plays its role in producing genetic variations?
• Important class 12 biology chapter 21 Assessment answers for Intermediate part-II students.
• Briefly explain prophase in mitosis.
• How malignant tumor or cancer is caused?

• Define cell cycle?  The cell under goes a sequence of changes, which involve period of growth, replication of DNA followed by cell division. This sequence of changes is called cell cycle.
• Important Class 12 Biology Chapter 21 Notes for Intermediate part-II students.
• What is metastasis?  The cell composing a malignant tumor or cancer, divide more rapidly, mostly invade surrounding tissues, get into the body circulatory system, and set up areas of proliferation, away from their site of original appearance. This spread of tumor cells and establishment of secondary a reas of growth is called metastasis.
• Define crossing over?  It is the exchange of segments between non-sister chromatids of homologous chromosomes due to chiasmata formation.
• Important biology chapter 7 Class 12 important questions and answers for Intermediate part-II students.
• What are symptoms of Turner's syndrome?  The affected individuals have one missing X chromosome with only 45 chromosomes (44 autosomes +Y). Individuals have female appearance with short stature, webbed neck, without ovaries and complete absence of germ cells.
• What is apoptosis?  Internal programme of events and sequence of morphological changes by which cell commits suicide is collectively called apoptosis ( Greek word that means dropping off or falling  off ).
• Important chapter 7 biology class 12 notes for Intermediate part-II students.
• What happens in G2-phase (pre-mitotic phase)? In G2 phase (pre-mitotic phase) the cell prepares for division i.e., energy storage for chromosome movements, mitosis specific proteins, RNA and microtubule subunits (for spindle fibres) synthesis are accomplished.
• Define mitosis?  It is the type of cell division, which ensures the same number of chromosomes in the daughter cells as that in the parent cells.