Multiple choice question (each part carries 1 mark; write the correct option in your answer book):

(क) Functional megaspore in a flowering plant develops into-
(i) Endosperm (ii) Ovule (iii) Embryo sac (iv) Embryo

(ख) The menstrual cycle in females is regulated by which hormone

Question

Multiple choice question (each part carries 1 mark; write the correct option in your answer book):

(क) Functional megaspore in a flowering plant develops into-
(i) Endosperm (ii) Ovule (iii) Embryo sac (iv) Embryo

(ख) The menstrual cycle in females is regulated by which hormones?
(i) Estrogen and Progesterone hormones (ii) Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) (iii) Luteinizing hormone (LH) and Testosterone (iv) Prolactin and Oxytocin

(ग) Which generation of Mendalian Cross has a phenotypic ratio of $3:1$?
(i) $F_0$ (ii) $F_1$ (iii) $F_2$ (iv) $F_3$

(घ) Which of the following is not a stage in the 'Hershey-Chase experiment'?
(i) Infection (ii) Conjugation (iii) Blending (iv) Centrifugation

(ङ) Antibody present in Colostrum that protect the newborn baby from disease is-
(i) IgA (ii) IgG (iii) IgD (iv) IgE

(च) Gene therapy was first used to treat which of the disease?
(i) Cancer (ii) AIDS (iii) Cystic fibrosis (iv) To overcome the deficiency of ADA

(छ) How many steps are there in the process of decomposition?
(i) 10 (ii) 2 (iii) 8 (iv) 5

(ज) What is the impact on the biodiversity of indigenous species when alien species are introduced into an area, either unintentionally or deliberately for any purpose?
(i) Decrease in alien species (ii) Increase in habitat (iii) They turn invasive and cause an increase in species. (iv) They turn invasive and cause the decline or extinction of indigenous species.

Direction: In the next two parts of Question No. 1, there are two statements labelled as Assertion (A) and Reason (R). From the following options select their correct answer:
(i) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(ii) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(iii) (A) is correct but (R) is incorrect.
(iv) Both (A) and (R) are incorrect.

(झ) Assertion (A): Marijuana and Hashish are clinically used as analgesic.
Reason (R): Both these drugs suppress brain's functionality.

(ञ) Assertion (A): Asexual reproduction is more important with regard to biotechnology.
Reason (R): Asexual reproduction preserves the genetic information while sexual reproduction permits variations.

Accepted Answer

>

> [!TLDR]
> क-(iii) Embryo sac · ख-(ii) FSH & LH · ग-(iii) F₂ · घ-(ii) Conjugation · ङ-(i) IgA · च-(iv) ADA deficiency · छ-(iv) 5 · ज-(iv) invasive decline of indigenous species · झ-(iv) both A & R incorrect · ञ-(i) both correct, R explains A.
>
> Concept & reasoning for each part (UBSE Class-12 Biology follows the NCERT/CBSE curriculum):
>
> (क) The functional megaspore enlarges and undergoes free-nuclear divisions to form the female gametophyte — the **embryo sac**. The other options are separate structures. → **(iii)**
> (ख) The menstrual cycle is driven by the pituitary gonadotropins that regulate the ovary; **FSH and LH** control follicular growth, ovulation and corpus luteum formation. → **(ii)**
> (ग) A monohybrid cross gives the classic $3:1$ phenotypic ratio in the **F₂** generation. → **(iii)**
> (घ) The Hershey–Chase experiment involved infection of bacteria by labelled phages, blending (agitation) and centrifugation. **Conjugation** is not a step. → **(ii)**
> (ङ) Colostrum, the first milk, is rich in **IgA** antibodies that protect the newborn. → **(i)**
> (च) Gene therapy was first used in 1990 on a girl to correct **ADA (adenosine deaminase) deficiency**. → **(iv)**
> (छ) Decomposition has **5** steps: fragmentation, leaching, catabolism, humification and mineralisation. → **(iv)**
> (ज) Introduced alien species often **turn invasive and cause the decline or extinction of indigenous species**. → **(iv)** …

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Q.Multiple choice question (each part carries 1 mark; write the correct option in your answer book): (क) Functional megaspore in a flowering plant develops into-

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