Which two main inflammation-causing chemicals are produced by the mast cells in such an immune response?
Solution and Explanation
Top Questions on Reproductive Health – Problems And Strategies
Student to attempt either option-(A) or (B):
(A) Study the given diagram showing the sectional view of a seminiferous tubule.
Answer the following questions:- [(i)] Label A, B, C and D in the figure.
- [(ii)] What will be the number of chromosomes in secondary spermatocyte and spermatid respectively?
- [(iii)] Explain the terms — Spermiogenesis and Spermiation.
OR
(B) Study the figures given below showing initial stages in the formation of female gametophyte and answer the questions that follow.
- [(i)] Identify (P) and (Q).
- [(ii)]
- [I.] What kind of division does cell (P) undergo to form (Q)?
- [II.] How many (Q) cells form the embryo sac? What is the name given to such kind of development?
- [III.] How many free nuclear mitotic divisions will the functional megaspore undergo to form the embryo sac?
- [IV.] Describe the structure of a mature female gametophyte.
- CBSE CLASS XII - 2025
- Biology
- Reproductive Health – Problems And Strategies
- A village health worker was taking a session with women. She tells them that one has to be careful while using oral pills as a method of birth control. Wrong usage can actually promote conception.
(A) Analyse the statement — oral pills need careful usage, as wrong usage can promote conception. Compare merits and demerits of using oral pills and surgical methods of birth control.
(B) Village women are confused as to how a thin metallic copper loop can prevent pregnancy. Explain the mode of action of IUDs. Give two points.- CBSE CLASS XII - 2025
- Biology
- Reproductive Health – Problems And Strategies
- Student to attempt either option (A) or (B):
(A) “A fully developed foetus initiates its delivery from the mother’s womb.” Explain.
OR
(B) Give reasons for the following:- Why can a woman generally not conceive a child after 50 years of age?
- Polar bodies are formed during oogenesis and not during spermatogenesis.
- CBSE CLASS XII - 2025
- Biology
- Reproductive Health – Problems And Strategies
- Explain how the intake of oral contraceptive pills prevent pregnancy in humans.
- CBSE CLASS XII - 2025
- Biology
- Reproductive Health – Problems And Strategies
- List two reasons that make copper releasing IUDs as effective contraceptives.
- CBSE CLASS XII - 2025
- Biology
- Reproductive Health – Problems And Strategies
Questions Asked in CBSE CLASS XII exam
- Find the general solution of the differential equation \[ y\log y\,\frac{dx}{dy}+x=\frac{2}{y}. \]
- CBSE CLASS XII - 2026
- Differential Equations
- A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of 60° in 0.2 s. The value of emf induced in the loop will be:
- CBSE CLASS XII - 2026
- Electromagnetic induction
A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following:
(i) Express \(y\) as a function of \(x\) from the given equation of ellipse.
(ii) Integrate the function obtained in (i) with respect to \(x\).
(iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration.
OR
(iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\).
- CBSE CLASS XII - 2026
- Integration
- Consider a cylindrical conductor of length \( l \) and area of cross-section \( A \). Current \( I \) is maintained in the conductor and electrons drift with velocity \( \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) \), where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
- CBSE CLASS XII - 2026
- Current Density
- The painting Hazrat Nizamuddin Auliya and Amir Khusro belongs to which sub-school of Deccan Miniature?
- CBSE CLASS XII - 2026
- Indian Miniature Paintings and Museums