Grade 12 : Biology - Sexual Reproduction (Plants/Humans) (Set 3) | Concept of Maths

Question 1

In an experimental plot of Oryza sativa, a researcher aims to produce exactly 600 viable seeds. What is the minimum number of meiotic divisions required to achieve this?

Accepted Answer

C) 750

Answer

A) 600

Answer

B) 150

Answer

D) 1200

Question 2

If the diploid chromosome number of a flowering plant is $2n = 36$, calculate the number of chromosomes present in the primary endosperm nucleus (PEN) and the synergid cell respectively.

Accepted Answer

B) 54 and 18

Answer

A) 36 and 18

Answer

C) 18 and 54

Answer

D) 72 and 36

Question 3

A patient has a regular menstrual cycle of 34 days. Based on the standard luteal phase duration, on which day is ovulation most likely to occur?

Accepted Answer

A) Day 20

Answer

B) Day 14

Answer

C) Day 17

Answer

D) Day 10

Question 4

During spermatogenesis, how many functional spermatozoa will be produced from 120 primary spermatocytes and 120 secondary spermatocytes respectively?

Accepted Answer

D) 480 and 240

Answer

A) 120 and 240

Answer

B) 480 and 480

Answer

C) 240 and 480

Question 5

In a typical 7-celled, 8-nucleate embryo sac, what is the ratio of haploid nuclei in the egg apparatus to the haploid nuclei in the antipodal cells?

Accepted Answer

B) $3:3$ (which simplifies to $1:1$)

Answer

A) $1:1$

Answer

C) $2:3$

Answer

D) $3:2$

Question 6

How many mitotic divisions are required for a single-celled human zygote to reach the 32-blastomere stage (Morula)?

Accepted Answer

C) 31

Answer

A) 32

Answer

B) 16

Answer

D) 5

Question 7

A gymnosperm plant has 20 chromosomes in its leaf cells. What will be the chromosome number in its endosperm?

Accepted Answer

A) 10

Answer

B) 20

Answer

C) 30

Answer

D) 40

Question 8

Which of the following depicts the correct sequence of ploidy levels for: Nucellus, MMC (Megaspore Mother Cell), Megaspore, and Female gametophyte?

Accepted Answer

D) $2n, 2n, n, n$

Answer

A) $n, 2n, n, 2n$

Answer

B) $2n, 2n, 2n, n$

Answer

C) $2n, n, n, n$

Question 9

If the starting concentration of HCG in a woman's blood is 50 mIU/mL and it doubles every 48 hours, what will be the concentration after 6 days?

Accepted Answer

B) 400 mIU/mL

Answer

A) 200 mIU/mL

Answer

C) 800 mIU/mL

Answer

D) 300 mIU/mL

Question 10

An apomictic plant produces seeds without fertilization. If the parent plant is $2n = 40$, what is the ploidy of the embryo and the endosperm (assuming autonomous endosperm formation from diploid nucellus)?

Accepted Answer

C) $40, 40$

Answer

A) $20, 30$

Answer

B) $40, 20$

Answer

D) $40, 60$

Question 11

Identify the incorrect statement regarding the human male reproductive system.

Accepted Answer

B) Leydig cells synthesize androgens under the influence of FSH.

Answer

A) Sertoli cells provide nutrition to germ cells.

Answer

C) The secretion of bulbourethral glands helps in lubrication.

Answer

D) Rete testis leads into vasa efferentia.

Question 12

In a pollen grain, the vegetative cell is larger and contains abundant food reserves, while the generative cell floats in its cytoplasm. If the vegetative cell has $X$ amount of DNA, what is the DNA content of the generative cell?

Accepted Answer

A) $X$

Answer

B) $2X$

Answer

C) $0.5X$

Answer

D) $4X$

Question 13

Cleistogamous flowers are strictly autogamous because:

Accepted Answer

C) They do not open at all, ensuring no cross-pollination.

Answer

A) They always open to expose anthers.

Answer

B) They require pollinators for seed set.

Answer

D) They produce nectar to attract specific bees.

Question 14

A woman underwent a procedure where her Fallopian tubes were surgically removed. Which of the following processes will be most directly hindered?

Accepted Answer

D) Fertilization

Answer

A) Ovulation

Answer

B) Menstruation

Answer

C) Implantation

Question 15

In a flowering plant, if the microspore mother cell has 24 chromosomes, what will be the number of chromosomes in the second male gamete and the zygote?

Accepted Answer

A) 12 and 24

Answer

B) 24 and 48

Answer

C) 12 and 36

Answer

D) 24 and 24

Question 16

How many total polar bodies are typically formed during the production of 10 functional ova in a human female?

Accepted Answer

C) 20 or 30 (depending on second meiosis)

Answer

A) 10

Answer

B) 20

Answer

D) 40

Question 17

If the length of a pollen tube increases at a rate of 2 mm/hour, how long will it take to reach an ovule located 1.4 cm away in the ovary?

Accepted Answer

B) 7 hours

Answer

A) 0.7 hours

Answer

C) 70 hours

Answer

D) 3.5 hours

Question 18

Which hormone is primarily responsible for the maintenance of the endometrium during the secretory phase of the menstrual cycle?

Accepted Answer

D) Progesterone

Answer

A) Estrogen

Answer

B) FSH

Answer

C) LH

Question 19

In a double fertilization event, if the pollen grain carries a mutation for 'Red flower' ($R$) and the egg cell carries 'White flower' ($r$), and the endosperm is triploid, what is the genotype of the endosperm (assume the mother plant is rr)?

Accepted Answer

A) rrr

Answer

B) Rrr

Answer

C) RRr

Answer

D) Rrr or RRr

Question 20

The part of the fallopian tube closest to the ovary is the:

Accepted Answer

C) Infundibulum

Answer

A) Isthmus

Answer

B) Ampulla

Answer

D) Cervix

Set 3Grade 12 : Biology - Sexual Reproduction (Plants/Humans)