Explore topic-wise InterviewSolutions in .

Spirogyra, (genus Spirogyra), any member of a genus of some 400 species of free-floating green algae (division Chlorophyta) found in freshwater environments around the world. Named for their beautiful spiral chloroplasts, spirogyras are filamentous algae that consist of thin unbranched chains of cylindrical cells. They can form masses that float near the surface of streams and ponds, buoyed by oxygen bubbles released during photosynthesis. They are commonly used in laboratory demonstrations.

Spirogyra species can reproduce both sexually and asexually. Asexual, or vegetative, reproduction occurs by simple fragmentation of the filaments. Sexual reproduction occurs by a process known as conjugation, in which cells of two filaments lying side by side are joined by outgrowths called conjugation tubes. This allows the contents of one cell to completely pass into and fuse with the contents of the other. The resulting fused cell (zygote) becomes surrounded by a thick wall and overwinters, while the vegetative filaments die.

Answer is : (d)

Philosophy and social commentary that deal with the biological sciences and their potential impact on society

The statement (d) is incorrect regarding significance of biopatents. It can be corrected as

Bioethics is the branch of ethics, philosophy and social commentary that deals with the biological sciences and their potential impact on society.

Answer is : (d)

The depletion of ozone layer leads to an increase in ground level ultraviolet radiation, because ozone is an effective absorber of ultraviolet radiation. The effects of ozone depletion include inhibition of photosynthesis in phytoplanktons which affects the food chains. It damages nucleic acids in living organisms (mutation). The ozone depletion causes an increase in UV radiations reaching the earth’ surface which can cause skin cancer.

Answer is : (b) Renal tubules and intestinal mucosa

Insulin increases glucose uptake in liver, leucocytes and smooth, cardiac and skeletal muscles. It does not do so in brain, renal tubules, intestinal mucosa and RBCs.

Answer : (c) T_A > T_C > T_B

Wien’s law, 

λ_m ∝ \(\frac{1}{T}\) 

And from the figure,

(λ_m)_A < (λ_m)_C < (λ_m)_B.

Therefore, 

T_A > T_C > T_B.

Answer : (c) 0.729 

The amplitude of damped oscillator is,

A = A₀e^-kt, 

Where k = \(\frac{b}{2m}\) 

At t = 5s, 

0.9 A₀ = A₀e^-5k

⇒ e^-5k = 0.9

At t = 15s, 

αA₀ = A₀e^-15k

⇒ e^-15k = α

⇒ e^(-5k)3 = α

⇒ α = (0.9)³

= 0.729

Answer is : (d)

All the pairs are correctly matched. The photosynthetic pigments in Chlorophyceae are chlorophyll-a and b carotenoids.

The photosynthetic pigments in Phaeophyceae are chlorophyll-a and c, fucoxanthin.

The photosynthetic pigments in Rhodophyceae are chlorophyll-a, phycocyanin, phycoerythrin and xanthophyll.

Answer is : (b) codominance

The MN blood group in humans is an example of codominance. In codominance, there is joint expression of both alleles in a heterozygote. In this situation, two alleles of a single gene are responsible for producing two distinct and detectable gene products.

Answer is : (d) Tumour-suppressor genes

Tumour-suppressor genes (e.g. p⁵³ gene) are very important to maintain the genomic integrity. They help in stopping division of cells having damaged DNA.

Answer is : (c) wider than efferent arteriole

In glomerulus, the afferent arteriole is shorter and wider than efferent arteriole which is longer and narrower.

Answer is : (c) Both (a) and (b) 

K-T boundary refers to the mass extinction of 60 million years ago when dinosaurs disappeared. 

It is connected with deposits of iridium which are rare on the earth.

Answer is : (c)

Phycophages are the viruses which are parasitic on algae. 

Mycophages are fungal viruses. 

Retroviruses carry enzyme reverse transcriptase. 

They have RNA genome. 

Tumour viruses cause benign and malignant tumours in animals and humans.

Answer is : (d) Hypoglossal – Sensory

Among the given options, option (d) is incorrectly matched. 

Hypoglossal is a motor nerve which controls the movements of the tongue. It originates from the ventral side of the medulla oblongata.

The correct answer is (2)

Mycoplasmas are smallest, prokaryotes lacking cell wall and are pleomorphic in nature. These are pathogenic to both plants and animals.

The correct answer is (1)

Horse belongs to 

Orders - Perissodactyla
Family - Equidae
Genus - Equus
Species - ferus
Subspecies - caballus

Answer is : (a) 1 63. ms⁻¹

Acceleration with which the cylinder rolls down,

\(a=\cfrac{g\,sin\theta}{1+\frac{l}{MR^2}}=\cfrac{g\,sin\theta}{1+\frac{\frac{1}{2}MR^2}{MR^2}}\) \(=\frac{2}{3}g\,sin\theta\) \(=\frac{2}{3}\times 9.8\times \frac{1}{20}\) \(=0.326\,ms^{-2}\)

Using first equation of motion,

v = u + at \(= 0 + 0.326\times 5\) \(=1.63\,ms^{-1}\)

Answer is : (d) isobarically

Work done is maximum, when process involved is isobaric.

Answer is : (b) angle between them can have any value other than zero or 180º

As, F = q(v x B) \(\Rightarrow\) F = qvB \(sin\,\theta\)

At \(\theta\) = 0°, F = 0

At \(\theta\) = 90°, F = qvB

 At \(\theta\) = 180°, F = 0

So, for non-zero force angle between v and B can have any value other than zero or 180°.

Answer is : (d) 5831t cm

Let the depth of Indian ocean is x cm

\(\therefore p_1V_1=p_2V_2(tdg+xdg)\)\(\left(\frac{4}{3}\pi r^3\right)\) \(=tdg\left[\frac{4}{3}\pi (18r)^3\right]\)

(t + x) = t x 18³

18³t - t = x 

So, x = t 5831 cm = 5831 t cm

Answer is : (a) 5 Ω

Output power will be maximum, if internal resistance of battery is equal to external resistance or load resistance, hence r = 5\(\Omega\).

Correct option is : (a) \(\frac{\triangle \varphi}{R}\)

Induced emf is given by

E_{ind = \(\frac{\triangle \varphi}{\triangle t}\)}

Current, i = \(\frac{Q}{\triangle t}\)

\(=\frac{\triangle \varphi}{\triangle t}\times \frac{1}{R}\)

\(\Rightarrow Q=\frac{\triangle \varphi}{R}\)

Answer is : (b) 29 m

For air, \(\rho\) = 1.10 kgm^-3

K = 1.32 x 10⁵ Nm^-2

Speed of sound in air,

v = \(\sqrt{\frac{K}{\rho}}\)

\(\sqrt{\frac{1.32\times 10^5}{1.10}}\)

= 3.46 x 10²

= 346 ms^-1

Answer is : (d) (i), (ii), (iii) and (iv)

All thermodynamic changes are zero.

Answer is : (d) 3.72 kg

Fall in temperature of brass sphere,

\(\triangle T\) = 500 - 0 = 500°C

Heat loss by sphere,

Q = \(ms\triangle T\) = 5 x 500 x 500

= 1250 kJ

Heat for melting m₂ kg of ice,

Q₂ = m₂L = m₂ x 336

From principle of calorimetry,

= 1250 kJ = m₂ x 336

m₂ = \(\frac{1250}{336}\) = 3.72 kg

Answer is : (d) 0.39 J

Heat produced in the resistor

= Energy of capacitor = \(\frac{1}{2}CV^2\)

= \(\frac{1}{2}\) x 6 x 10^-6 x 360 x 360

= 0 39 J

Answer is : (d) \(T\propto (r_1+r_2)^{\frac{3}{2}}\)

The semi-major axis of the elliptical orbit around the sun is given by

\(r=\frac{r_1+r_2}{2}\)

According to Kepler’s third law,

\(T^2\propto r^3\)

\(\Rightarrow T^2\propto (\frac{r_1+r_2}{2})^3\)

\(or\: T\propto (\frac{r_1+r_2}{2})^\frac{3}{2}\)

\(or\:T\propto (r_1+r_2)^{\frac{3}{2}}\)

Answer is : (d) \(\frac{k}{2x^2}\)

As, I = \(\frac{-dV}{dr}\)

⇒ dV = - ldr

So, \(\int\limits^v_0 dV\) = \(\int\limits^x_0\) - ldr = \(\int\limits^x_0\) - kr^-3 dr

⇒ V = - k\(\left(\cfrac{r^{-3+1}}{-3+1}\right)^x_0\)

= \(\frac{k}{2x^2}\)