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
, 1  2017
10) Mention the key features of Meiosis.
A. The key features of Meiosis are :
1. Meiosis involves two sequential cycles of nuclear
and cell division called meiosis-I and meiosis-II
but only a single cycle of DNA replication.
2. Meiosis-I is initiated after the parental
chromosomes have replicated to produce identical
sister chromatids at the S-phase.
3. Meiosis involves pairing of homologous
chromosomes.
4. Occurrence of crossing over and chiasmata.
5. Occurrence of recombination between non sister
chromatids of homologous chromo-somes in a
bivalent leads to variations which are important
for the process of evolution.
6. Random separation or segregation of homologous
chromosomes takes place.
7. Separation of sister chromatids in Anaphase-II.
8. Four haploid cells are formed at the end of.
Meiosis-II.
Describe the structure of power houses of cell ?
BOTANY
4 MARKS IMPORTANT
QUESTIONS & ANSWERS
1) Explain Binomial Nomenclature.
A. The system of providing a correct scientific
name with two components is called
binomial nomenclature. According to
this system each name has two components
the generic name and Specific name.
Binomial nomenclature is introduced by
Gaspard Bauhin, but this naming system
popularized by Carolus Linnaeus.
Eg: Scientific name of mango is written as
Mangifera indica. Mangifera represents
genus while indica represents species or
Specific epithet.
Some of the universal rules of nomenclature:
1. Biological names are generally in Latin or
in latinised form.
2. In a biological name the first word is genus
and second word is species or specific
epithet.
3. Both the words of biological name are
underlined separately if they are hand
written or printed in italics to indicate their
latin origin
4. Genus starts with capital letter while the
species starts with small letter.
5. Name of the author (the person or scientist
who gave that name) appears after the
specific epithet, i.e., at the end of the
biological name and is written in an
abbreviated form, e.g., Mangifera indica
Linn. Linn indicates that this species was
first described by Linnaeus.
2) Give the salient features and importance
of Chrysophytes.
A. 1. This group includes diatoms and
desmids or golden algae.
2. They are aquatic, microscopic, float
passively in water currents.
3. Most of them are photosynthetic.
4. In diatoms, cell wall contains two thin over
lapping shells-epitheca and hypotheca.
Cell walls are embedded with silica.
5. Diatoms reproduce asexually binary
fission, sexually by gametes.
6. During sexual reproduction, auxospores
are formed as a rejuvenatory spores.
7. After death diatoms left large amount of
cell wall deposits in their habitat and forms
diatomaceous earth.
8. Diatoms are divided into two types based
on their structural symmetry, the central
diatoms are radially symmetrical and
pennales are bilaterally symmetrical.
4) Write a brief account on gametogenesls,
with examples.
A. 1. The process by which diploid (or) haploid
precursor cells undergo cell division and
differentiation to form mature haploid (n)
gametes is called gametogenesis.
2. In organisms belonging to Fungi, Algae
and Bryophytes, plant body is haploid, but
in organisms belonging to Pteridophytes,
Gymnosperms and Angiosperms, the plant
body is diploid.
3. A haploid (n) parent produces gametes by
mitotic division. In diploid organisms,
specialised cells called meiocytes as
gamete mother cells (2n)/ spore mother
cells (2n) undergo meiosis to form (n)
gametes with only one set of chromosomes.
4. In some Algae, the two gametes are so
3) Differentiate between red algae and brown algae.
Red algae-Rhodophyceae
Brown algae-Pheophyceae
1. These algae have a red pigment,
r-phycoerythrin
2. Thallus is multicellular and some of
them are with complex organization.
3. They have chlorophyll a, d, phyco
erythrin as major pigments.
4. Food is stored as floridan starch,
structurally similar to amylopection
& glycogen
5. Cell walls are made up of cellucose
pectin and polysulphate esters.
6. Vegetative reproduction takes place by
fragmentation and asexual reproduction
is carried by non-motile spores.
1. These algae vary in colour from olive green to
various shades of brown colour according to
the amount of xanthophylls and fucoxanthin.
2. Some are simple branched filamentous
(Ectocarpus) to profusely branched filamentous
forms (kelps) with a height of 100 meters.
7. Sexual reproduction is oogamy. Male
sex organ gives non flagellated male
gamete called spernatium and female
sex organ is flask shaped called as
carpogonium.
7. Sexual reproduction occurs by isogamy,
anisogamy or oogamy. Union of gametes
occurs in water or within the oogonium.
Gametes are pyriform with two laterally
attached flagella.
3. They have chlorophyll a, c, carotenoids and
xanthyophylls as their pigments.
4. Food is stored in the form of Iaminarin or mannitol.
5. Cell wall is made up of cellulose and algin.
6. They reproduce vegetatively by fragmentation
and asexually by pear shaped, biflagellated
zoospores, having unequal flagella.
similar in appearance that it is not possible
to categorize them into male and female
gametes, hence they are called Homogametes (or) Isogametes.
E.g. Cladophora
5. In a majority of sexually reproducing
organisms, the gametes produced are of
two morphologically distinct types, hence
they are called Heterogametes.
6. In such organisms, the male gamete is called
antherozoid/sperm (n) and the female
gamete is called the egg (n)/ovum (n).
Eg: Funaria, Pteris, Cycas
5) Describe the essential floral
parts
of
plants
belonging to Liliaceae.
A. Essential floral parts
Jr.Inter
include androecium and
SPl
gynoecium.
Androecium: Six stamens in
two whorls of 3 + 3, anthers are
dithecous, basifixed, introrse and
dehiscence is longitudinal.
Gynoecium: Tricarpellary, syncarpous;
superior ovary, trilocular with many ovules
on axile placentation. Style is terminal,
stigma trifid and capitate.
6) Give economic importance of plants
belonging to Fabaceae
A. 1. Many plants belonging to the family are
good source of proteins (pulses like
redgram, blackgram)
2. Edible oils (soybean, groundnut)
3. Vegetables (Pods of bean, soybean: seeds of
garden pea, groundnut : leaves of Menthi),
4. Timber (Red sanders, Indian rose wood)
5. Fiber (sunhemp)
6. Other commercially important products
obtained viz., blue dye (Indigo feratinctoria),
yellow dye (Butea monosperma, commonly
called flame of the forest); medicine (Derris
indica); fodder (Crotalaria, Phaseolus) or
green manure (Sesbania, Tephrosia).
7) Describe the structure and function of
power houses of cell.
A. ‘Mitochondria’ are commonly called
power houses of cell.
Mitochondria occur in all eukaryotic cells,
Typically it is sausage-shaped (or)
cylindrical having a diameter of 0.2-1.0µm
and length in about 1.0-4.1µm.
Mitochondrion is a double membrane
bounded cell organelle and the space
present between two membrames is called
as peri mitochondrial space.
Outer membrane forms the continous
limiting boundary of the organelle and the
inner membrane forms a number of
infoldings called as cristae towards the
matrix.Inner space of mitochondria filled
with fluid matrix which contains circular,
naked dsDNA and RNA, 70S ribosomes
and respiratory enzymes.
Many stalked particles present of the surface of
the cristae are called F0 – F1 particles.
Krebs cycle of aerobic respiration occurs in
matrix and electron transport takes place
in cristae.
Nakirekanti Seenaiah
BASARA
MEDICAL ACADEMY
Hyd
94403 78146
Functions:
1. Mitochondria are concerned with cellular
respiration and involved in oxidation of
food material
2. They store energy in the form of ATP and
hence called power houses of cell.
8) Give a brief account of the types of
chromosomes based on the position of
centromere.
A. A chromosome with one centromere is
called monocentric chromosome.
Based on the position of centromere,
monocentric chromosomes are four types
a) Metacentric: Centromere present in the
middle point of the chromosome. So both
arms of the chromosomes are equal in
length. Chromosome appears ‘V’ shaped
during anaphase of cell division
b) Sub-metacentric: Centromere is slightly
away from the centre of the chromosome.
So, chromosome has two unequal arms.
During anaphase such chromosomes appear
as ‘L’ shaped.
c) Acrocentric: In a chromosome centromere
is situated close to its end forming one
extremely short and one very long arm. So
chromosomes appear as ‘J’ shaped during
anaphase.
d) Telocentric: Centromere is present at the
terminal end of chromosome. So telec entric chromosome has only one arm. Duri
-ng anaphase it appears ‘I’ shaped.
9) Nucleic acid exhibits secondary structure,
Justify with example.
A. 1. One of the secondary structures exhibited
by DNA is of Watson-Crick model.
2. According to this model, DNA exists as
double helix.
3. The two polynucleotide strands are
antiparallel i.e., run in opposite direction.
4. The backbone is formed by the sugarphosphate-sugar chain.
5. N2 –bases are projected-perpendicular to
the back bone, but face inside.
6. Adenine (A) and Guanine (G) of one strand
pair with Thymine (T) and Cytosine (C) of
other strand, respectively.
7. Two hydrogen bonds are present in
between A and T. Three hydrogen bonds
are present in between G and C.
8. Each strand looks like a helical staircase, Each
step is represented by a pair of N2 –bases.
9. At each step of ascent, the strand turns 360.
10. Ten steps or ten base pairs are present in
one full turn of the helix.
11. The pitch would be 34 A0, The distance
between two successive base pairs would
be 3.4 A0