Kerala Plus Two Answer Key 2023 Botany

SECOND YEAR

Kerala Board
Answer Key
2023

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ANSWER KEY IcodeNol SY526 I
SECOND YEAR HIGHER SECONDARY EXAMINATION MARCH 2023
PART -III
SUBJECT: BOTANY
30 SCORES 1 HOUR
Total
Qn. No. Sub Qn. Answer Key I Value Points Score
Score
PART I 1 - 5 (Any 3) 3x1=3
1 Perisperm 1 1
2 Fragmentation I Decomposition 1 1
Gel electrophoresis I Agarose gel electrophoresis I
3 1 1
Electrophoresis

4 Commensalism 1 1
5 cry1Ab 1 1
PART II 6 - 16 (Any 9) 9 x 2 = 18
Grazing Food Chain I GFC Detritus Food Chain I DFC
Begins with Green plants / Begins with dead organic
producers. matter / detritus
Major conduit for energy 1+1 2
6 Major conduit for energy
transfer in terrestrial
transfer in aquatic ecosystems.
ecosystems.
(Anyone points in each type)
or (Flow chart showing GFC and DFC give 1 score each)
• Pollen release and stigma receptivity are not synchronized /
(Anther & stigma mature at different time).
• Anther and stigma are placed at different position.
• Self-incompatibility / (genetic mechanism to prevent pollen
7 germination I genetic mechanism to prevent pollen tube 1+1 2
formation)
• Production of unisexual flowers.

• Male and female flowers are present on different plant /
(dioecy) (Any 2 points)

• Bacterial cells are treated with specific concentration of
divalent cation such as Ca2+ (to increase cell permeability).

• Then these cells are treated with recombinant DNA (rONA)
on ice. ~x4
8 2
• The cells and rONA in ice are allowed to heat at 42°C (heat
shock at 42°C).
• Put them back on ice (which enables bacteria to take up the
Recombinant DNA).

(a) Funicle Y2

(b) Micropyle Y2 2
9
(c) Embryo sac / Female gametophyte Y2
(d) Chalaza Y2
(a) Taq polymerase 1
10 2
(b) Thermus aquaticus 1
Rate of biomass / Organic matter production is called
1
productiviy.
Factors affecting primary productivity
11 The plant species inhabiting a particular area 2
Environmental factors (SunlightlTemperaturelWater /C02) Y2x 2
Availability of nutrients
Photosynthetic capacity of plants. (any 2 factors)
The Bt toxin is produced by the bacteria as inactive protoxin.
When an insect ingest the inactive toxin, it is converted into an
active toxin due to the alkaline pH of the gut which solubilise
12 the crystals. 1+1 2
The activated toxin binds to the surface of midgut epithelial
cells and create pores that cause cell swelling and lysis and
eventually leads to death of the insect.

(a) Mutualism Y2

(b) Parasitism Y2
13 2
(c) Commensalism Y2

(d) Mutualism / Symbiosis Y2

When energy flow from a particular trophic level to the next
level some energy is lost as heat at each step.
14 2 2
Only 10% of the energy is transferred to each trophic level
from the lower trophic level. ( Any 1 point give full score)

Genetically Modified Organism (GMO) - Organisms whose
genes have been altered by manipulation are called 1
Genetically Modified Organisms.

• Made crops more tolerant to abiotic stresses
• reduce the reliance on chemical pesticides ( Pest resistant
15 crops) 2
• Helped to reduce post harvest losses 1
• Increased efficiency of mineral usage by plants
• Enhanced nutritional value of food / Golden rice / Vitamin A
enriched rice.
• Used to create tailor made plants to supply alternative
resources to industries. (any 1 merit)

(a) Exponential growth / Geometric growth curve / J shaped
curve Y2
(a)
16 (b) Logistic growth / Verhulst-Pearl Logistic Growth / Sigmoid 2
Growth curve / S shaped curve
Y2

(b) K - Carrying capacity 1
PART III 17 - 20 (Any 3) 3x3=9
• Eli Lilly prepared DNA sequences corresponding to A and B
chains of insulin.
• Introduced them in plasmid of E.coli to produce insulin
1x 3
17 chains. 3
• Chain A and B were produced separately.
• Chain A and B were extracted and combined by creating
disulfide bonds to form human insulin

• Pollen grains are light and non-sticky.
• Flowers possess well exposed stamens.
• Large feathery stigma
• Single ovule in each ovary
18 • Numerous flowers packed into an inflorescence. 1x 3 3
• Plants produces large amount of pollen
• Flowers are colourless
• Odourless (Do not have smell)
• Nectarless (Any three points)
(a) - Mortality / 0 Y2
(i)
(b) - Emigration / E Y2
19 Natality / B Y2 3
(ii)
Immigration / I Y2
(iii) Natality refers to the number of births during a given period 1

• The first letter 'E' comes from the genus / Escherichia

• The second two letters come from the species of the
prokaryote / bacteria / coli
20 1+1+1 3
• The letter 'R' is derived from the name of strain / RY 13
• Roman number indicates the order in which the enzyme
isolated from that strain of bacteria. (Any 3 points carries 1
score each)

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