Here are 9 common mistakes shared by her which can help you get close to getting 100 per cent in the CBSE Class 12 Biology Board exam:

1. Not utilizing the reading time fruitfully

• Fifteen minutes is enough time to read the CBSE Class 12 Biology question-paper thoroughly and plan out strategies to frame answers in the best possible way

• Also, concentrated reading will result in vivid scrutiny of all the part questions or sub-questions of a long question and thereby minimize errors and question drops.

2. Writing in paragraph form

• Students should abstain from writing in paragraph form. Answers should always be written in point-wise manner in the CBSE Class 12 Biology Board exam, using bullets or arrows

• Also, students should underline/highlight the important terms used, thereby facilitating the examiner to evaluate in a better manner and fairly

• Long answers should be preferably written in schematic or flowchart form.

3. Avoiding pictorial/diagrammatic illustrations

• CBSE Biology and the subject of Bio-science prefers the use of diagrams at various levels. 2-mark, 3-mark and 5-mark questions should be accompanied by diagrams wherever possible as CBSE gives importance to diagrams

• Diagrams have to be labeled. Students should preferably use pencil for drawing and labeling. Labels should all be on the right side of the diagram

4. Forgetting to cite examples

The NCERT book has several examples of types, patterns, flora and fauna for CBSE Class 12 Biology. While answering, those examples need to be given as the marking scheme has marks allotted for the same.

5. Tendency of writing more than required

• CBSE puts a lot of stress on writing to the point and not exceeding word limit

• If two marks are allotted, only two points have to be mentioned

• Writing excess in the Class 12 Biology Board exam will not only result in loss of time but might also lead to the deduction of marks awarded to the answer

6. Haphazard pattern of answering

Writing answers serially is the ideal approach. However, many students tend to jump from one section to another, without completing that particular section. This can irritate the examiner leading to improper marking.

7. Tendency of writing till the stroke of the bell

• A combined effect of excess writing, stress, and fear leads to improper time management

• By writing until the end of the Board exam, the student fails to conserve time for revision or for pondering on HOTS questions.

8. Improper detailing of value-based questions

• Just stating facts in this section is not justified for the CBSE Class 12 Biology Board exam

• Answers to such questions need to have a touch of life skills or values.

9. Neglecting NCERT text material

• Students have a tendency to avoid details and examples of the NCERT book and prefer citing information from reference books. Little do they know that the marking scheme sent by the board is 100 per cent based on NCERT, and Board examiners have to adhere to the marking scheme while correcting Board papers

• Thorough reading of the NCERT is mandatory to succeed in CBSE Biology Board exam.

Read: CBSE Class 12 Physics Board Exam: Board examiner points out 9 common mistakes students lose marks for
Read: CBSE Class 12 Chemistry Board Exam: Board examiner lists common mistakes students lose marks for
Read: CBSE Class 12 English paper: 14 tips from board examiner to help you easily score over 90

XII - BIOLOGY

SUPPORT MA

TERIAL

FOR BIOLOGY

FOR

CLASS XII

Members of W

riting T

eam

Sl.

No.

Name Designation Sc

hool

1.

Mr

. S.D. Sharma

Principal

Rajkiya Pratibha V

ikas V

idyalaya,

(T

eam Leader)

Raj Niwas Marg, Delhi-1

10054

(9868341

155)

2.

Mr

. Ranveer

Singh

Lecturer (Biology)

Sarvodaya Bal V

idyalaya

(9891069977)

T

imar Pur

, Delhi-1

10054

3.

Mr

. R.P

. Singh

Lecturer(Biology)

Rajkiya Pratibha V

ikas

(M. 9990081661)

V

idyalaya,Kishan Ganj,

Delhi.1

10007

4.

Mrs. Sarita Singh

Lecturer (Biology

Rajkiya Pratibha V

ikas

(9871356271)

V

idyalaya, Shalimar Bagh,

Delhi-1

10088

5.

Mr

. V

.S. Malik

Lecturer

Rajkiya Pratibha V

ikas

(9868162341)

(Biology)

V

idyalaya, Civil Lines,

Delhi-1

10054

6.

Mr

. Reetesh Gupta

Lecturer

Rajkiya Pratibha V

ikas

(981

1690031)

(Biology)

V

idyalaya,Surajmal V

ihar

,

Delhi 1

10092

7.

Mrs.

Alka Panwar

Lecturer

S.A.C Govt. Sarvodaya

(9868828998)

(Biology)

V

idyalaya, Shamnath

Marg,

Delhi-1

10054

1

Class-XII

Biology (Theory)

Design of the Question Paper

Maximum Marks : 70

T

ime : 3 hours

The

weightage

of

the

distribution

of

marks

over

dif

ferent

dimensions

of

the question paper shall be as follows :

1.

W

eightage of Contents / Subject Units

Units

Content

Mark

VI

Reproduction

14

VII

Genetics and Evolution

18

VIII

Biology and Human W

elfare

14

IX

Biotechnology and its application

10

X

Ecology and Environment

14

T

otal

70

2.

W

eightage of Different Form of Questions

S.No.

Form of Questions

Marks

No. of

T

o

t

a

l

for each

Questions

Marks

1.

V

ery Short

Answer (VSA)

1

08

08

2.

Short

Answer (SA

II)

2

10

20

3.

Short

Answer (SA

I)

3

09

27

4.

Long

Answer (LA)

5

03

15

T

otal .

-

30

70

3.

Scheme of Option

1.

Three will be no overall option.

2.

Inter

nal

choice

(either/or

type)

on

a

v

er

y

selectiv

e

basis

has

been

pro

vided.

The

choice

has

been

giv

en

in

one

question

of

2

mar

ks

,

one

question

of

3

mar

ks

and

all

the

three

questions

of

5

mar

ks

w

eightage

.

4.

W

eightage to difficulty level of questions

S. No.

Estimated Dif

ficulty Level

Percentage

1.

Easy

15

2.

A

v

er

age

70

3.

Difficult

15

About 20%

w

eightage has

been assigned

to questions

testing higher

order

thinking skills of lear

ners

.

?

The

question

paper

will

include

v

alue

Based

Question

(s)

to

the

e

xtent

of

3-5 mar

ks

XII - BIOLOGY

2

CONTENTS

S. No.

Chapter

1.

Reproduction in Organisms

2.

Sexual Reproduction in Flowering Plants

3.

Human Reproduction

4.

Reproductive Health

5.

Principles of Inheritance and V

ariation

6.

Molecular Basis of Inheritance

7.

Evolution

8.

Human Health and Disease

9.

Strategies for Enhancement in Food Production

10.

Microbes in Human W

elfare

1

1.

Biotechnology : Principles and Processes

12.

Biotechnology and Its

Applications

13.

Organisms and Populations

14.

Ecosystem

15.

Biodiversity and Conservation

16.

Environmental Issues

Model Papers

CBSE Paper 2012-2013

XII - BIOLOGY

3

CHAPTER 1

REPRODUCTION IN ORGANISMS

POINTS T

O REMEMBER

Clone

:

A

group

of

organism

derived

from

a

single

individual

and

hence

morphologically

and

genetically

similar

.

Embryogenesis

:

The

process

of

development

of

embryo

from

zygote.

Juvenile

Phase

:

It

is

the

period

of

growth

before

maturity

when

sex

organs

are

not

functional.

Meiocytes

:

These

are

specialized

cells

of

diploid

organisms

which

undergo

meiosis.

Pericarp

:

It

is

the

protective

covering

of

fruit,

may

be

divided

into

epicarp,

mesocarp

and

endocarp.

Parthenogenesis

:

Development

of

an

egg

into

an

embryo

without

fertilisation.

XII - BIOLOGY

In single Celld organisms

In algae, fungi and lower animals

V

egetative propagation

Assexual Reproduction

Runner e.g. Oxalis

Rhizome e.g. Ginger

Sucker e.g. Banana

Of

fset e.g. W

ater hyacinth

Bulb e.g. Onion

Leaf e.g. Bryophyllum

Bulbil e.g.

Agave

Binary fission e.g.

Amoeba

Multiple fission e.g.

Plasmodium

Zoospore e.g.

Chlamydomonas

Conidia e.g.

Penicillium

Bud e.g. Hydra

Gemmules e.g. Sponge

Fragmentation e.g. Spirogyra

4

Gamete T

ransfer

1.

In

Algae,

Bryophytes

and

Pteridophytes

:

The

male

and

female

gametes

are

flagellated

and

motile,

need

a

medium

(water)

to

reach

the

egg.

2.

In

seed

Plants

:

Pollen

grains

are

transferred

to

stigma

of

flower

of

same

species

by

various

agents.

3.

In

animals

:

(a)

By

Copulation

.

e.g.,

Reptiles,

Birds

and

Mammals.

(b)

By

External

medium

.

e.g.,

Fishes

and

Amphibians.

Sporulation

:-

During

unfavorable

conditions

organisms

like

Amoeba

surrounded

by

resistant

coat

(three

layered

-

hard

covering

)

or

cyst.

This

is

called

encystation

.

Within

cyst

a

number

of

spores

are

formed

.

On

returning

favourable

conditions,

the

cyst

burt

and

spores

are

liberated

and

gradually

grows

into

adults.

This

process

is

known

as

sporulation.

Fragmentation :

It is

a type of

asexual reproduction

where an

organism

splits

into

fragments.

There

fragments

develops

into

fully

grown

individual.

eg.

spirogyra,

fungi

and

some

annelids.

Regeneration:

It

is

a

process

of

renewal,

restoration

and

growth.

It

can

occur

at

the

level

of

the

cell

tissue

and

organ

.

It

is

common

in

Hydra

,

Planaria

and

echinoderms

.

ü

In

human,

liver

has

power

of

regeneration,

if

it

is

partially

damaged.

ü

During

danger

a

lizard

discard

a

part

of

tail

which

can

regenerate

latter

.

QUESTIONS

VSA

(1 MARK)

1.

Of

fsprings

produced

by

asexual

reproduction

are

referred

to

as

clones

Why?

2.

Name

the

most

invasive

aquatic

plant

weed

which

is

called

as

.'T

error

of

Bengal'.

3.

How

does

Zygote

usually

dif

fer

from

Zoospore

in

terms

of

ploidy?

4.

Mention

the

main

dif

ference

between

the

of

fspring

produced

by

a

s

e

x

u

a

l

r

e

p

r

o

d

u

c

t

i

o

n

a

n

d

p

r

o

g

e

n

y

p

r

o

d

u

c

e

d

b

y

s

e

x

u

a

l

reproduction.

XII - BIOLOGY

5

5.

Which

characteristic

property

of

Bryophyllum

is

exploited

by

gardeners

and

farmers?

SA

II (2Marks)

6.

Higher

organisms

have

resorted

to

sexual

reproduction

inspite

of

its

complexity

.

Why?

7.

T

apeworms

possess

both

male

and

female

reproductive

organs.

What

is

the

name

given

to

such

organisms?

Give

two

more

examples

of

such

organisms.

8.

Study

the

relationship

between

first

two

words

and

suggest

a

suitable

word

for

fourth

place.

(a)

Male

flower

:

Stamens

::

Female

Flower

:

.............................

(b)

Birds

:

oviparous

::

Primates

:

.............................

(c)

Chlamydomonas : Zoospores :: Penicilium :

.....................

(d)

Ginger

:

Rhizome

::

Agave

:

.............................

9.

Bryophytes

and

Pteridophytes

produce

a

large

number

of

male

gametes

but

relatively

very

few

female

gametes.

Why?

SA

I (3 Marks)

10.

Mention

the

site

of

zygote

formation

in

the

ovule

of

a

flowering

plant.

What

happens

to

sepals,

petals

and

stamens

after

fertilisation?

State

the

fate

of

zygote,

ovule

and

ovary

in

these

plants.

1

1.

Distinguish

between

gametogenesis

and

embryogenesis.

12.

Fill

the

blank

spaces

a,

b,

c,

and

d

given

in

the

following

table.

Organism

Organ

Gamete

a

T

estes

Spermatozoa

Human

female

b

Ovum

Plant

(Angiosperm)

c

Pollen

grains

Plant

(Pteridophyte)

antheridium

d

XII - BIOLOGY

6