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#### Locus of the midpoint of any focal chord of $\mathrm{y}^2=4 \mathrm{ax}$ is  Option: 1 $\mathrm{y}^2=\mathrm{a}(\mathrm{x}-2 \mathrm{a})$  Option: 2 $\mathrm{y}^2=2 \mathrm{a}(\mathrm{x}-2 \mathrm{a})$  Option: 3 $\mathrm{y}^2=2 \mathrm{a}(\mathrm{x}-\mathrm{a})$  Option: 4 $\text{None of these}$

Let the midpoint be $\mathrm{P}(\mathrm{h}, \mathrm{k})$. Equation of this chord is $\mathrm{\mathrm{T}=\mathrm{S}_1}$. i.e., $\mathrm{\mathrm{yk}-2 \mathrm{a}(\mathrm{x}+\mathrm{h})=\mathrm{k}^2-4 \mathrm{ah}}$. It must pass through $(\mathrm{a}, 0)$

$\mathrm{\Rightarrow 2 \mathrm{a}(\mathrm{a}+\mathrm{h})=\mathrm{k}^2-4 \mathrm{ah}}$. Thus required locus is $\mathrm{\mathrm{y}^2=2 \mathrm{ax}-2 \mathrm{a}^2.}$

Hence option 2 is correct.

#### A massless string connects two pulley of masses ' $2 \mathrm{~kg}$' and '$1 \mathrm{~kg}$' respectively as shown in the figure.The heavier pulley is fixed and free to rotate about its central axis while the other is free to rotate as well as translate. Find the acceleration of the lower pulley if the system was released from the rest. [Given, $g=10 \mathrm{~m} / \mathrm{s}^2$]Option: 1 $\frac{4}{3} \mathrm{~gm} / \mathrm{s}^2$Option: 2 $\frac{3}{2} \mathrm{~gm} / \mathrm{s}^2$Option: 3 $\frac{3}{4} \mathrm{~gm} / \mathrm{s}^2$Option: 4 $\frac{2}{3} \mathrm{~gm} / \mathrm{s}^2$

Not understanding sir

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#### The following is the biochemical pathway for purple pigment production in flowers of sweet pea:Colorless precursor 1 —- Allele A—->  Colorless precursor 2 —--- Allele B—---> Purple pigmentRecessive mutation of either gene A or B leads to the formation of white flowers. A cross is made between two parents with the genotype: AaBb × aabb. Considering that the two genes are not linked, the phenotypes of the expected progenies are:Option: 1 9 purple : 7 whiteOption: 2 3 white : 1 purpleOption: 3 1 purple : 1 whiteOption: 4 9 purple : 6 light purple : 1 white

3(white):1(purple)

In case of 'duplicate recessive epistasis homozygous recessive gene masks the other gene i.e., aa is epistatic to A or a || bb is epistatic to B or b

1.32

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2

#### When cell has stalled DNA replication fork, which checkpoint should be predominantly activated?Option: 1 G1/S Option: 2 G2/M   Option: 3 M Option: 4 Both G2 M and M

G2/M should be activated as the cell has stalled DNA replication fork.

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Option 2

150

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#### If $x=\sum_{n=0}^{\infty }(-1)^{n}\tan ^{2n}\theta \: \: and\: \: y=\sum_{n=0}^{\infty }\cos ^{2n}\theta ,$ for $0<\theta < \frac{\pi }{4},$ then Option: 1 Option: 2 Option: 3 Option: 4

$x=\sum_{n=0}^{\infty}(-1)^{n} \tan ^{2 n} \theta=1-\tan^2\theta+\tan^4\theta..........$

$y=\sum_{n=0}^{\infty} \cos ^{2 n} \theta=1+\cos^2\theta+\cos^4\theta......$

Use $\text S_{\infty}=\frac{1}{1-r}$

${x=\frac{1}{1+\tan ^{2} \alpha}=\cos ^{2} \theta} \\ {y=\frac{1}{1-\cos ^{2} \theta}=\frac{1}{\sin ^{2} \theta}}$

$\Rightarrow (1-x)= \sin ^{2} \theta$

$\Rightarrow y(1-x)=1$

Correct Option (3)

Option d