3 Marks Question

Question 13 Marks

Given below is an equation describing the Species$-$Area relationship between species richness and area for a wide variety of taxa as angiosperm plants, birds, bats etc.
$S = CA^Z$
$a.$ Give a graphical representation of the given equation showing Species$-$Area relationship.
$b.$ What does $S$ represent in the given equation?
$c.$ What is the value of $Z \ ($regression coefficient$)$ for frugivorous birds and mammals in the tropical forests of different continents?

Answer

$a.$ The given equation's graphical representation of the relationship between species and area is as follows:

$b.$ The species richness is represented by $S$ in the given equation.
$c.$ The regression coefficient $Z$ is the slope of the line. The slope is found to be $1.15$ for frugivorous $($fruit$-$eating$)$ birds and mammals in tropical woods on various continents.

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Question 23 Marks

Do you support dope test being conducted on sports persons participating in a prestigious athletic meet? Give three reasons in support of your answer.

Answer

Yes, the 'dope test' should be conducted on sports persons participating in a prestigious athletic meet. This is done to find out if any participant had taken any kind of performance enhancing drugs. The use of drugs in sports should be banned as:
i. they increase muscle strength.
ii. promote aggressiveness
iii. increase athletic performance
Because of above reasons, use of such drugs, e.g. steroids, analgesics, diuretics should be banned for participants as it would be unfair on the part of other participants (not consuming such drugs).

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Question 33 Marks

Who proposed the term evolution? What is evolution? List the different evidences in support of evolution.

Answer

→ The term evolution is considered to be used by Charles Lyell initially. But the theory of evolution was proposed by Charles Darwin.
→ Evolution signifies "Descent with modification" which means the process of inheritable changes in any species over several generations.
→ There are many pieces of evidence which support the evolution. Few are:
- Homologous and analogous structures
- Molecular biology related evidence where shared ancestry of life has been reflected by DNA and genetic code in different species.
- Biogeography related evidence showing speciation due to geographical isolation.
- Fossils records from different geological timelines.

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Question 43 Marks

Forests provide intangible benefits to us. Explain by taking three different areas, how.

Answer

$i.$ Improvement of climate: The influence of forests on things like wind, temperature, rainfall, and humidity is improved. They control the water cycle, $O_2, CO_2$ balance in the atmosphere, and temperature.
$ii.$ Control of flood: Forests prevent flooding by minimising erosion on sloping hills and silting up in lakes, rivers, and other reservoirs.
$iii.$ Aesthetic, recreational and development of tourism facilities: Any person, especially those who live in cities, can find
relief from their repetitive lives in forests.
$iv.$ Conservation and development of wildlife including birds: In terms of shelter, a place to reproduce, and a supply of food, forests are the optimal environment for wildlife.

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Question 53 Marks

a. Given below is the stepwise schematic representation of the process of electrophoresis. Identify the alphabets representing (i) Anode end (ii) smallest/lightest DNA strand in the matrix (iii) Agarose gel

b. What is elution? State the importance of elution in this process.

Answer

a. i. Anode = S
ii. Smallest/lightest DNA Strand = R
iii. Agarose gel = T
b. The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with cloning vectors.

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Question 63 Marks

Study the table showing the population interaction between species Z and Y respectively. Assign the appropriate +/- signs for A, B, D, E and respective interactions for C and F.

Species 'Z'	Species 'Y'	Name of Interaction
A	B	Mutualism
-	-	C
D	E	Parasitism
+	O	F

Answer

A = +
B = +
C = Competition
D = +
E = -
F = Commensalism

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Question 73 Marks

Why is the frequency of red-green color blindness is many times higher in males than that in females?

Answer

The genes that produce photopigments are present on X-chromosomes. If some of the genes are missing or damaged, it can result in colour blindness. Since males have only one X-chromosome, the chances of colour blindness are very high in males. In the case of females, to be colourblind must have the allele for it in both her X-chromosomes. In case, if female possesses the allele for colourblind in only one X-chromosome, then she will act as a carrier and won't be affected by it.

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Question 83 Marks

Given below is a schematic representation of a lac operon. Answer the following questions:

i. Identify i and p.
ii. Name the inducer for this operon.
iii. Explain the function of inducer for this operon.

Answer

The Inducer is lactose.
iii. Functions of Lactose
a. Enters the cell and binds to the repressor and inactivates it.
b. As a result, repressor cannot bind to the operator. This allows RNA polymerase to have access to the promoter and transcription proceeds.

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BIOLOGY 3 Marks Question

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