Botany Solved Past Paper 2nd year 2013 Karachi Board


1. Choose the correct answer for each from the given options

i) Naturally occuring cytokinin Is:
* Zeatin
* Kinetin
* Ethene
* Auxin

ii) The cotyledon of maize Is:
* Integument
* Coleoptile
* Coleorhiza
* Scutellum

iii) The number of bases of genetic code used to specify an ~mino acid is:
* One
* Two
* Three 
* Four

iv) Promotion of flowering by cold treatment Is called:
* Apomixis
* photoperiodism
* Vernalization
* Phototropism

v) The correct sequence of sub-stages during Interphase Is:
* G G2S
* SG G2
* G SG2
* G2 G S

vi) This bacterium is found In the root nodules of leguminous plants:
* Azotobacter
* Clostridium
* Rhizobium
* Cyanobacterium

vii) Diabetes Is caused due to the defici.ncy of:
* Thyroxin
* Pepsin
* Insulin
* Bile

viii) Programmed cell death is:
* Apoptasis
* Phagocytosis
* Necrosis
* Pinocytosis

ix) The plants living in fresh water are termed as:
* Mesophytes
* Halophytes
* Hydrophytes
* Xerophytes

x) Above 40°C, plant cell starts synthesizing:
* Lipid
* Enzyme
* Hormone
* Heat shock protein

xi) Dark zone of oceanic region Is:
* Euphotic
* Aphotic
* Abysal
* Bathyal

xii) In the stem secondary growth Is caused due to the activity of:
* Cambium
* Xylem
* Phloem
* Pith

xiii) Each chromosome is attached to the spindle fibre with the help of:
* Centriole
* Aster
* Cell plate
* Kinetochore

xiv) This biome is called the bread basket of the world:
* Savannah
* Grassland
* Desert
* Tundra

xv) Ecosystem having Lotic water is called:
* Pond
* Swamp
* River
* Tundra

xvi) Exudation of water by hydathode is:
* Transpiration
* Excretion
* Guttation
* Respiration


2.i) Describe Biological clock and Circadian system in plants

Biological clock: All living organisms have a sense to control their activities in time keeping manner and regulate their activities by physioloqical and metabolical activities called clock system. The independent time measuring activities in an organism is called
Biological Clock.
Living organism shows the behavioral or biological activities at regular intervals is called Biological Rhythm.
Circadian System: The biological Rhythm which brought about with a frequency of 24 hours is called circadian Rhythm.
(Latin, Circa = about, dies = day)
Circadian Rhythm also called Diuranal Rhythm, as it occurs in 24 hours due to day and nigh

ii) Write a note on Sclerenchyma tissues.

Sclerenchyma type of supporting tissues. They are simple Sclerenchyma fundamental tissues. On maturity (a) TS most of them become dead. They have uniformly thick, heavily lignified Nucleus secondary walls, which give strength to the plant body. Often these walls are so thick that the lumen of the cell becomesnearly vanished. Tracheids are the long and cylindrical cells found in xylem, while vessels are long tubular sclerenchyma cells join end to end to form long water conducting pipe in xylem. These spindles shaped dead thick walled tracheids, vessels and elongated fibrous cells of xylem and phloem also provide strength to
lamand leaf.



iii) Differentiate between Mitosis and Meiosis.
Ans: See on Page # 459.

iv) Draw a chart showing geno types and pheno types of different Blood Groups 

different blood gruop

different blood gruop

v) Write a note on positive or negative interaction in Organisms.
Positive Interactions: In this type of interaction in which living organisms interact with each other for mutual benefit to get food or I shelter or for support etc. In this benefit may be for both organisms or one can get benefit and other neither get benefit nor harm.
Example: Mutualism, commensalism Negative Interactions: This is a type of interaction in which living organisms interact with each other and cause harm to one of them for getting food, shelter or support or may compete for other resource.
Example: Predation, Grazing

vi) Write a note on Co-dominance or incomplete dominance.
Co-dominance The phenomenon in which both the contrasting characters are dominant and express themselves in heterozygous condition is called co-dominance. In this, individuals neither masking the effect of one another.
Example: When true breeding red-skin cattle (Bull) and white-skin cattle (Cow), resulting off springs have roan colour. The cfose examination of the roan skin showed the mixture of red and white hair, but not the intermediate of the two shades. Self-fertilization of roan skined animal results the phenotypic ratio same as that of genotypic ratio. i-e 1:2:1 that result 1 red animal 2 roan (mixture of red + white) and 1 white skined animal.
Incomplete dominance: The phenomenon in which neither of the contrasting character is dominant oyer each other resulting the mixture or a blend of two characters. This is also known as Blending Inheritance or Partial Dominance.
Example: When true breeding red flower and true breeding white flowers of four o’clock plants (Mirabulus jalapa) are crossed, all the plants in F1 generation carry pink coloured flowers. When these F1 hybrid self crossed results red, pink and white flowers in the ratio of 1 :2:1 i.e., phenotypic and genotypic ratio is the same.

vii) Write a note on Chromosomal aberration.
Ans: See on Page # 459.

viii) Describe natural methods of Asexual Reproduction in plants.
Ans: See on Page # 458.

ix) Write a note on any ONE of the following Ecosystems:
(a) Savannah
A Savannah ecosystem is defined as the ecosystem with mixed communities of grasses and patches of scattered trees. Savannah is term applied for tropical grass lands.
Occurane: Major Savannah biomes of world are found in African countries, Australia, South India, South America.
1. Annual rainfall is about 125 cm. per year.
2. Distinct prolonged dry season.
3 Temperature ranges more than 18°C throughout the year. During dry season, there is extensive fires.
4. Grass is much taller usually 3.5 m long.
5. Grass catches fire during dry season.
6. Seasons are regulated by rainfall rather than temperature.

(b) Tundra

Ans: Tundra means open forest-less country.
Occurane: Tundra ranges from 66.60-720 north and south latitudes and
covers such parts of world as iceland, southern greenland, Alaska,
Canada, Siberia etc.
Kinds: There are two main typs of tundra biome.
1. Arctic tundra (surround arctic ocean)
2. Alpine tundra (above timberline upto ice caps to mountains).

Low temp is characteristics. ie 10°C to -57°C .
Short growing season .
Ground usually remains frozen except for upper 10-20 cm .
Permanently deeper frozen soil is called as perma frost layer found
below 10-20 cm of tundra soil.
During winter season, sun does’t rise for several months .
During summer seasons sun does’t set for an equal period of months .
Wind velocity in alpine tundra is about 160J r:!.hrand intense ultra violet radiation.
Tundra Plants: (Producers): In low tundra there is thick spongy mat of living vegetation and is saturated with water .
The predominant plants are lichens, mosses, grasse’S and sedges .
Small herbs and shrubs also found in tundra .
Southern slopes also possess flowering herbs like Aconite and Geranium.

Tundra Animals (Consumers): The animals who have adopted to live In tundra are caribou, reindeer, arctic hare, arctic fox, polar beer, wolf etc .
During summer there are mosquitoes flies are hosts of migratoy birds .
The caribou and reindeer are highly migratory because there is not
enough vegelation to support them.

(c) Coniferous forests
The coniferous forest characterized by cold resistant, evergreen plants belonging to gymnosperm.
Occurrence: This kind of forest covers predominantly northem hemisphere that include from Alaska to central America which is heavily glaciated. While few in southem hemisphere.
There is heavy snow fall during winter. .
Plants show xerophytic features, like needle leaves .
Plants grow slowly .
Low decomposition of dead plants and animals.
Rainfall is fairly heavy.· .
Producers: The main plants of the forest are pine, fir and spruce, Dicot plants include Bisch willwo and Populus found in this area.
Consumers: Black bears and flying squirrals are common animals in the forest.

x) Define Photoperiodism.
The plants responses to light period (Photo period) is called photo periodism. One of the important photo periodic response is flowering in flowering plants.
There are three types of plants according to photoperiod.
1- Short-day plants
2- Long-day plants
3- Day-neutral plants.

xi) What are Tropic movements? Name different types of tropic
The word tropic is derived from Greek word “Tropos” meaning “turn” In this condition, the whole part or organ show growth or curvature movement.
Tropic movements are in response of unidirectional stimuli. It is clearly seen in symmetrical parts of the plants, such as root and shoot.
On the basis of stimulus nature, it is further divided into following types.
A- Phototropism: This type of tropic movement causes due to
unidirectional effect of light. It is also known as Heliotropism.
i- Positive Phototropism
ii- Negative Phototropism
B- Geotropism: It is the movement of growth curvature causes in response to gravitational stimulus.
i- Positive Geotropism
ii- Negative ;otropism

xii) Draw a chart showing different zones in the sea.
Ocean covers about 70% of earth surface. It is the greatest reservoir of nutreints and living organisms.
Horizontally sea can be divided into two zones, neritic and oceanic
1) Oceanic Zone: It is further divided vertically in two major zones
a- Euphotic b- Aphotic

a) Euphotic Zone: It is the region of oceanic zone in which sun light
reaches to the living organisms and is transparent zone.
b) Aphotic Zone: It is’ non photosynthetic and dark zone of oceanic region which comprises into upper region bathyal zone and lower is abyssal zone, plant life is totally absent.
i- Bathyal Zone: It is vertical region upto the depth of about 2000 meters.
ii- Abyssal Zone: It is the lower verticle region of oceanic zone below the 2000 meters depth. I
2) Neritic Zone: It is the shallow water found at the edge of continental shelf and upto the depth of 180 meters. It is further divided into.
Supratidal: It is the high tidal zone of neratic ocean.
Sub-tidal/lnter-tidal: It is the intermediate or intertidal zone at in between high and low tide of neratic zone.
Low tidal: It is below the low tide’ line region of the neratic ocean. I Neratic ocean is the most productive zone of the sea and enough sunlight penetrates in it. Additionally, oxygen, carbondioxide and other riutreints are also helpful for the growth ot plants



xiii) What is Gibberellin? Give its role

Gibberellins are produced commercially from fungal cultures of Gibberella fujikorii

Role of Gibberellins:

1. Cell elongation
2. Bolting: Certain plants like carrot, show profuse development of leaves but retardation in growth of internode. It is called “Rossette” type of growth. Just before the reproductive stage, there is a striking stimulation of internode elongation ~d- sometimes the internode elongates 5-6 times of original height~~led boltinq,
3. May induce Parthenocarpy. ‘.
4. To help in flowering and development of fruits;
5. To help in the conversion of biennial into annual plants
6. To increase the size and number of fruits such as lemon, orange,
grapes etc.
7. To break the dormancy of seeds, buds and underground parts e.g, bulb, tuber, com.
8. Increase the size and number of flowers.
9. They also stimulate bud sprouting.
10. The growth of pollen tube also stimulate by GA

Commercial Application:
1. GA promotes fruit setting.
2. GAJ is used in brewing industry.
3. To delay ripening and improve storage life of some fruits e.g.,
Banana and Grapes.

xiv) Define various types of RNA.
See on Page # 461.

xv) Write a note on Genetic Code.
The coded message from DNA in the form of base triplet carried by RNA for protein synthesis is known as “Genetic Code”.
There are four nitrogenous bases•.in ‘DNA that is adenine (A), Cytosine (C), Guanine (G), and Thymine (T). Silltilarly, in RNA there are also four nitrogenous bases which are adenine (A) Cystosine (C), Guanine (G) and Uracil (U).
Genetic code was calcuted by assuming different conditions from 4
nucleotide for 20 basic aininoacids.


Write a note on different approaches used for Ecological Investigation.

Approaches to Ecology: There are several factors, which interact in a particular locality, due to this there are several approaches to undertake ecological investigations. Each approach has its own merits and demerits. Thus etologists use one of the suitable approach to understand ecological phenomenon. These approaches are population approach or autecology, community approach or synecology, ecosystem’ approach, habitat approach, evolutionary and historical approach.

a. Population approach (Autecology): This approach is based on the study of individual species, it accounts for the interrelationship between an individual species and its environment. Thus the unit of population approach is individual species.
b. Community approach (Synecology): Instead of studying single or individual species the whole coramunity and its environment is considered for ecological studies. Therefore, the study of different communities, their relation between them and their environment is called synecology. This type of study has developed the concept of succession and climax i.e. progressive replacement of one community by more stable community and growth of it in a particular area.
c. Ecosystem approach: This is the most recent development in ecology. Ecosystem is the highest level of biological organization, all ecological concept can be set within this framework. This approactt is based on two things, the flow of energy and cycling of matter between living and non-living components. This system introduces a concept of seJf-regulationand self-sufficiency. Thus living organisms and their nonliving environment interact in amost coordinated form and any disturbance may lead to biological disturbance.
d. Habitat approach: The organism is adapted to particular physical condition of the habitat e.g. a shaHow, fast moving cold water stream may be the habitat of a species of trout. This approach is easy to define hence it is widely used. 1l\e study of physical environment ike •. soil,· moisture, temperature and light is also convenient to study. It car1 be further divided into micro habitats or smal habitats with their own special conditions.
e. Evolutionary approach: This approach is linked with evolutionary trend. It tells us about changes since life evoIve4 and may predict the future changes. ~, thi6 study also needs the use of fossil records.
f. Historical approach: ” deals with changes associated with the development of tools in man’s history. Thus its period Starts wiIh stone age i.e. 1500 to 3000 B.C. (Neolithic period). Through this approadt long term ecological planning is done and new trends can be pointed out.

3ii) Describe Watson and CrIci model 01DNA and its NpliC8lion.
Ana: See on Page # 465. ‘

3iii) What are Phyto hormones? Gift names of different of hormones.
Describe only two types of hormones.
Sorne of the spada: substance produced by the pJanIs which influence the growth and plant responses to various stimuli ate caJfed ·Plant Hormones” or Phytohormones:
Some important plant hormones are as under. .
Auxins: Auxins are indole acetic acid (IAA) or their variants chemically. Role of Auxins:
1. Ir. stem, promote ceOenlargement in region behind apex, Promote cell division in cambium,
2. In root. promote growt.hat!very low concentrations, inhibits growth at higher concerezatlons ~g: Geotropism, promote growth of roots from cutting and f~lhJSes. ‘
3. Promote bud in/tRiClonin shoots but sometimes antagonistic to
cytokinins and inhibitory.
4. Sometime promote bud Lilliputian in intact plant if apical dominance broken.
5. Promote apical ‘dominance and fruit growth.
6. It can sometimes induce parthenocarpy.
7. Causes delay in leaf senescenece in few species.
8. It inhibits Abscission.
9. It acts as weed killer.
10. It also control dormany in seeds.
11. Overcome sterility.
12. Shortening of internodes occurs due to auxins.

Gibberellins: Gibberellins are produced commercially from fungal
cultures of Gibberella fujikorii.
Role of Gibberellins
1. Cell elongation
2.Bolting: Certain plants like carrot, show- profuse dellelopmenl leaves but retardation in growth internode. It is called Rossette· type of growth. Just before the reproductive stage, there is a striking stimulation of intemode elongation and sometimes the internode elongates 5-6 times of orginal height called bolting.
3. May induce Parthenocarpy.
4. To help in flowering and development of fruits.
5. To help in the conversion of biennial into annual plants.
6. To increase the size and number of fruits such as lemon, orange”
grapes etc.
7. To break the- dormancy of seeds, buds and underground parts e..g. bulb, tuber, corn.
8. Increase the size and number of flowers.
9. They also stimulate bud sprouting.
10. The growth of pollen tube also stimulate by GA.

Commercial Application
1. GA promotes fruit setting.
2. GA3 is used in brewing industry.
3. To delay ripening and improve storage life of some fruits e.g…
Banana and Grapes.

Cytokinis: Cytokinins are first obtained from coconut milk (plant) and from Herring sperm DNA (animal) and yeast (fungi) extract. Zeatin is naturally occuring cytokinin, obtained from corn grains in the form oIf crystals. Kinetin is a synthetic one: Cytokinins induce cell division in the presence of auxine.
Abscisic Acid (ABA): It is known as growth inhibitor, produce in stress conditions, such as drought conditions.
Ethene: It is another growth regulator which help in fruit ripening, and is only a gaseous hormone.

OR Discuss Sex-linked inheritance in Humans.
In human beings there are 23 pairs of chromosomes. Out of which 22 pairs of chromosomes are autosomes and the remaining 23rd pair is morphologically different in male and femal is called sex-chromosome.. There are about 200 genes present oil- X-chromosome. There are two most popular sex-linked traits found .in human beings i.e., colourblindness and haemophilia.

a- Colour-Blindness: It is a sex-linked inheritance found in human beings. In this condition colour blind person cannot distinguish red colour from green. It is more common in males and rare in females.

There are some possible results of various crosses.

N= normal
n= coleur-bllnd

Colour Blind Male Vs Normal Female

Colour Blind Male Vs Normal Female

Normailiale Vs Carrier Female

Normailiale Vs Carrier Female

Explanation: When a colourblind male marreis with a carrier female, 50% offsprings normal and 50% offsprings colourblind. Moreover, 25% normal carrier female, 25% normal son, 25% colour blind son and 25% colour blind females

Posted on December 30, 2015 in 2nd Year 2013 Karachi Board Past Papers

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