12th Standard Biology English Medium Free Online Test One Mark Questions with Answer Key 2020 - Part Eight | QB365

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12th Standard Biology English Medium Free Online Test One Mark Questions with Answer Key 2020 - Part Eight

Published on: 05/11/2020

Download Tamil Nadu 12th Standard Biology question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.

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Questions:

Multiple Choice Question

25 x 1 = 25

Watson and Crick proposed their double helical DNA model based on the X-ray diffraction analysis of _________

(a)

Erwin Chargaff

(b)

Meselson and Stahl

(c)

Wilkins and Franklin

(d)

Griffith

Which of the following statement is not correct?
(i) Interstitial cells are seen surrounding the seminiferous tubule.
(ii) Nurse cells secrete inhibin.
(iii) Males have single prostate gland which encircles the urethra.
(iv) Insemination, Fertilization, Implantation, Placentation, and Parturition.

(a)

i and ii

(b)

iii only

(c)

iii and iv

(d)

iv only

Which of the following approach does not give the defined action of contraceptive?

(a)

a) Barrier methods

Prevent fertilizers

(b)

b) Intra uterine devices

Increases phagocytosis of sperms suppresses sperm motility and fertilizing capacity of sperms.

(c)

c) Hormonal contraceptives

Prevent retard entry of sperms, prevent ovulation and fertilization.

(d)

d) Vasectomy

Prevents spermatogenesis

Test tube baby is got by _____ technique.

(a)

IUI

(b)

CVS

(c)

ICSI

(d)

IVF

The unequal divisions during oogenesis results in small cells called ______

(a)

oogonia

(b)

primary oocyte

(c)

secondary oocyte

(d)

polar bodies

The ______ is the smallest human cell.

(a)

sperm

(b)

neuron

(c)

nephron

(d)

alveoli

In honey bees, the mode of reproduction is

(a)

Sexual and Asexual

(b)

Sexual and Parthenogenesis

(c)

Asexual and Parthenogenesis

(d)

All the above

__________ was first reported by John Cotto.

(a)

Erythroblastosis foetalis

(b)

Haemophilia

(c)

Colour blindness

(d)

Haplodiploidy

Desired improved variety of economically useful crops are raised by _______.

(a)

Natural Selection

(b)

hybridization

(c)

mutation

(d)

biofertilisers

10.

Which of the following is / are not the mechanism of decomposition

(a)

Eluviation

(b)

Catabolism

(c)

Anabolism

(d)

fragmentation

11.

Strong, sharp spines that get attached to animal’s feet are found in the fruits of ______.

(a)

Argemone

(b)

Ecballium

(c)

Heritier

(d)

Crossandra

12.

Read the given statements and select the correct option.
Statement A : Cattle do not graze on weeds of Calotropis.
Statement B : Calotropis have thorns and spines, as defense against herbivores.

(a)

Both statements A and B are incorrect.

(b)

Statement A is correct but statement B is incorrect

(c)

Both statements A and B are correct but statement B is not the correct explanation of statement A.

(d)

Both statements A and B are correct and statement B is the correct explanation of statement A.

13.

As per 2017 statistics, the highest per capita emitter of Carbon dioxide in the world is

(a)

USA

(b)

China

(c)

Qatar

(d)

Saudi Arabia

14.

Which of the following is not involved in nitrogen fixation?

(a)

Pseudomonas

(b)

Azotobacter

(c)

Anabaena

(d)

Nostac

15.

The Neanderthal man had the brain capacity of

(a)

650 – 800cc

(b)

1200cc

(c)

900cc

(d)

1400cc

16.

An analysis of chromosomal DNA using the southern hybridisation technique does not use _____.

(a)

Electrophoresis

(b)

Blotting

(c)

Autoradiography

(d)

Polymerase Chain Reaction

17.

An operon is a: ______.

(a)

Protein that suppresses gene expression

(b)

Protein that accelerates gene expression

(c)

Cluster of structural genes with related function

(d)

Gene that switched other genes on or off

18.

The process which the sperm undergoes before penetrating the ovum is _____.

(a)

Spermiation

(b)

Cortical reaction

(c)

Spermiogenesis

(d)

Capacitation

19.

The site of embryo implantation is the _____.

(a)

Uterus

(b)

Peritoneal cavity

(c)

Vagina

(d)

Fallopian tube

20.

Improvement of human race by encouraging the healthy persons to marry early and produce large number of children is called

(a)

Positive eugenics

(b)

Negative eugenics

(c)

Positive euthenics

(d)

Positive euphenics

21.

AIDS virus has

(a)

Single stranded RNA

(b)

Double stranded RNA

(c)

Single stranded DNA

(d)

Double stranded DNA

22.

Assertion (A): Gamma rays are generally use to induce mutation in wheat varieties.
Reason (R): Because they carry lower energy to non-ionize electrons from atom

(a)

A and R are correct

(b)

A is correct. R is wrong

(c)

A is wrong. R is correct

(d)

A and R are wrong

23.

Which of the following phenotypes in the progeny are possible from the parental combination AxB?

(a)

A and B only