Plus Two Botany Model Question Papers Paper 2

Plus Two Botany Model Question Papers Paper 2 is part of Plus Two Botany Previous Year Question Papers and Answers. Here we have given Plus Two Botany Model Question Papers Paper 2

Plus Two Botany Model Question Papers Paper 2

Time: 1 Hours
Cool off time : 10 Minutes

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off,time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question’itself.                  ,
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

(Questions 1 to 2): Answer all questions. Each questions carries 1 score.

Question 1.
From the following, select the two having haploid chromosome number.
a. egg
b. endosperm
c. zygote
d. pollen

Question 2.
Bt Cotton is regarded as an important achievment of genetic engineering. What does Bt stands for?

(Questions 3 to 15) : Answer any eleven questions from the following. Each questions carries 2 score.

Question 3.
Ecological pyramids are usually upright. Meanwhile some, pyramid of biomass is inverted. Explain the reason.

Question 4.
Figure representing the reactions associated with Polymer Chain Reaction (PCR). Name the steps A, B, C in the process.

Question 5.
Recombinant DNA technology can be accomplished only if we have the following key tools ie., Restriction enzymes, Polymerase enzyme, Ligases and Vectors. State the functions of
a. Ligases
b. Restriction enzymes

Question 6.
Match the following

Question 7.
Given below are the components related to simplified model of mineral cycling in a terrestrial ecosystem. Construct a flow chart.
(Hint : weathering of rock)

Question 8.
Primary succession of rocks is known as Xerosere. Answer the following related with Xerosere.
a. Name the pioneer community.
b. Organic acids have important roles in this succession. Justify.

Question 9.
An aquatic ecosystem having luxurious growth of cyanobacteria (Algal bloom) leads to eutrophication.
a. What kind of pollutants cause algal bloom to colonize the aquatic ecosystem?
b. What are the consequences of eutrophication ?

Question 10.
A list of different organisms in an ecosystem are given below. Arrange them in 1st, 2nd, 3rd and 4th trophic level.
i. Phytoplankton
ii. Man
iii. Fish
iv. Zooplankton

Question 11.
Use of thermostable DNA polymerase from the bacterium, Thermus aquaticus, made it possible to generate billion copies of DNA in a very short time using a process.
a. Name the process.
b. Name the three important steps in volved in this process.

Question 12.
Read the statements below and identify the mode of interaction between the species.
a. Tiger eating deer.
b. Butterfly feeding pollen.
c. Human liver fluke feeding on snail.
d. Lice on humans.
e. Orchid attached to a tree.
f. Mycorrhizal association of fungi and roots of higher plants.
g. Sparrow eating seed.
h. Egrets foraging close to cattle.

Question 13.
Environmentalists usually says: “There are may causes for biodiversity losses”. Illustrate four major causes of biodiversity loss.

Question 14.
In a marine ecosystem, a population of phytoplankton (1,50,000) supports a standing crop of fishes (40,000).
a. Draw the pyramid of biomass.
b. Draw the pyramid of numbers in this ecosystem.

Question 15.
Geetha resides in a city nearby a lake. Water from this lake was used for various domestic purposes earlier. Now-a- days, this water has become turbid and is with an unpleasant odour.
a. What can be the reason for this?
b. Name the scientific term that explains this effect.

(Questions 16 to 18): Write any two from the following questions. Each questions carries 3 score.

Question 16.
Raju is a diabetic patient who takes insulin injections regularly. The insulin used by such patients is produced by genetically engineered organism. Write the different steps involved in the production of insulin by genetic engineering.

Question 17.
Raman is learning the post-fertilization changes of an angiosperm embryosac with the help of slides. He identified the egg nucleus and polar nuclei with the help of his teacher.
a. Name the other nuclei present in the embryosac.
b. Help Raman by giving the changes that takes place with egg nucleus and polar nuclei after fertilization.

Question 18.
Given below is the bar diagram showing age structure of three different populations. Observe the diagram carefully and answer the following questions.

Answers

Answer 1.
egg, pollen

Answer 2.
B – Bacillus
T – thuringiensis

Answer 3.
In most ecosystems, all the pyramids, of number, of energy and biomass are upright, i.e., producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores. Also energy at a lower trophic level is always more than at a higher level.
The pyramid of biomass in sea is also generally inverted because the biomass of fishes far exceeds that of phytoplankton. Pyramid of energy is always upright, can never be inverted, because when energy flows from a particular trophic level to the next trophic level.

Answer 4.
A – Denaturation
B – Annealing,
C – Primer extension

Answer 5.
a. Ligases are enzymes that can rejoin
cut fragments of DNA by sealing the sugar-phosphate back bone,
b. These are the molecular scissors that cut long DNA at specific points, into smaller fragments.
Restriction enzymes belong to a larger class of enzymes called nucleases.

Answer 6.
i. 4
ii. 1
iii. 2
iv. 3

Answer 7.

Answer 8.
a. Lichens are the pioneer community.
b. Lichens secrete acids to dissolve the rock, helping in weathering and soil formation.

Answer 9.
a. Due to the addition of domestic
sewage, water bodies become rich in nutrient content. Addition of nutrients stimulates profuse growth of planktonic algae (free-floating algae).
b. Luxuriant growth of algal bloom totally cover the water surface. This causes reduction in DO (dissolved oxygen content). Decomposition of algal blooms causes deficiency of 02 in water. Algal blooms also release some toxins in water. Toxins inhibit the growth of other algae in bloom infected water body. So, in this poor oxygenated water with high level of CO₂, fishes and other aquatic animals begins to die due to the toxicity.

Answer 10.

Answer 11.
a. PCR (Polymerase chain reaction).
b. Step I – Denaturation,
Step II – Annealing,
Step III – Primer extension.

Answer 12.
Predation:

1. Tiger eating deer
2. Sparrow eating seed

Commensalism:

1. Orchid attached to a tree
2. Egrets foraging close to cattle

Parasitism:

1. Human liver fluke feeds on snail
2. Lice on humans

Mutualism:

1. Butterfly feeding pollen.
2. Mycorrhizal association of fungi and roots of higher plants.

Answer 13.
Major cause of biodiversity loss are:

1. Habitat loss and fragmentation: Due to the loss of natural habitat or use of natural habitat of animals or plants for other purposes will decrease the biodiversity in that area.
2. Co-extinction: Extinction of an organism or tree may cause the extinction of other organisms or plants that depends on it.
3. Over exploitation: With the over use of natural resources the biodiversity decreases in earth.
4. Alien species invasion: The species that enter in a new area when compete with the indigenous species results in the decrease in the species or extinction of indegeneous species

Answer 14.

Answer 15.
a. Domestic sewage and fertilizers add large quantities of nutrients in the lake. The rich supply of these nutrient increased productivity of water bodies i.e., algal blooming or nutrient enrichment. The decomposed water has become turbid and is with an unpleasant odour.
b. Eutrophication.

Answer 16.

1. 1st two DNA sequences corresponding to A and B chains of human insulin are prepared.
2. They are introduced into plasmids of E-coli to produce insulin chain.
3. Chains A and B were produced separately.
4. Extracted and combined by creating disulphide bonds to form human insulin.

Answer 17.
a. Synergids and antipodals.
b. One of the two male gametes fuses with the egg to form zygote (2n).
The other male gametes fuses with the secondary nucleus to form endosperm which is triploid.

Answer 18.
a. B is stable.
b. A- Pre-reproductive: High percentage of young individual positive growth and board based age pyramid.
B- Reproductive: Growth rate is slow and stable, ie., zero growth. It is belt shaped polygon.
C- Post reproductive: Growth rate is decline, negative growth phase. An urn-shaped figure.

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