Question Discussion & Solution

Concept:

Resistance: The property of electrical materials and electrical instruments that opposes the flow of current through them is called resistance.

It is denoted by R. The SI unit of resistance is the ohm (Ω).

Power: The rate of work done by an electric current is called power. It is denoted by P. The SI unit of power is the watt (W).

Power dissipation (P) is given by:

\(P=VI=\frac{V^2}{R}=I^2R\)

Where V is the potential difference across resistance, I is current flowing and R is resistance.

Calculation:

With R = 50 Ω, and V = 220 V, the power required by the bulb will be:

\(P=\frac{V^2}{R}=\frac{220\times 220}{50}\)

P = 968 W

Eagle, Bird, Crocodile

All Eagle is the Bird and Crocodile is the reptile. 

So,  Venn diagram given bellow-

Hence, option 4 is the correct answer.

Concept:

• Nutrition is a process by which an organism consumes and uses food materials.
• According to WHO, Nutrition is the intake of food, considered in relation to the body's dietary needs.
• There are various modes of nutrition mainly Autotrophic, Heterotrophic, Chemoautotrophic, Saprophytic,  etc.

Explanation:

• Holophytic or autotrophic nutrition: In this type of nutrition the organisms prepare their food by themselves. Eg - green plants.
• Plants prepare their food by the process called photosynthesis. 
• During photosynthesis, plants trap solar energy or light energy with the help of chloroplast present in the green leaves and convert it into Chemical energy
• A pigment called chlorophyll is present in the chloroplasts which are required in trapping sunlight
• Plants utilize Carbon dioxide and Water for the synthesis of carbohydrates during photosynthesis, oxygen is liberated as a side product
• This gaseous exchange occurs through the stomata present on the leaf surface

• These events can be demonstrated by the following equation:

  \(\rm \underset{(Carbon\ dioxide)}{6CO_2} + \underset{(Water)}{6H_2 O} \xrightarrow[Chlorophyll]{Sunlight} \underset{(Carbohydrates)}{C_6H_{12}O_6} + \underset{(Oxygen)}{6O_2}\)

Therefore, Plants require CO₂, Chlorophyll, Sunlight and water for autotrophic nutrition and hence the correct option will be ''All of these''.

Concept-

Vestigial organs are the organs that once were useful in an animal's body millions of years ago, but now they are useless or very close to useless.

Key Points Human heart-

• The human heart is not vestigial as at present times it has its own functions in the human body.
• The human heart is an organ that pumps blood throughout the body.
• Heart pumps the blood through the vessels of the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes.
• The tissues of the body need a constant supply of nutrition in order to be active which is performed by blood.

Additional Information Wisdom teeth

• Wisdom teeth are no longer totally necessary. Today, humans cook food to soften it, and we can cut and crush it with utensils.So at this time they are vestigial.
• Early humans needed to chew coarse, hearty foods, they required a broader jaw.
• Wisdom teeth grew in to give them more chewing power for this purpose.

Nictitating membrane of eye

• In humans, the nictitating membrane is the pink lump in the inner corner of the eyes which is known as the caruncula lacrimalis.
• In this structure, the remaining of the nictitating membrane are permanently folded into that corner and no longer functional.So it is vestigial.

Vermiform appendix

• The human appendix may be considered as a vestigial organ as it has been proved that the removal of the organ after infancy does not create any harm.
• Its function is to digest cellulose.

CONCEPT:

• Power: The rate of work done is called power.
  • It is denoted by P.
  • Mathematically it is written as

\(Power\;\left( P \right) = \frac{{\;W}}{{t}}\)

CALCULATION:

Given - mass of 1^st person (m₁) = 80 kg, mass of 2^nd person (m2) = 60 kg, time (t₁) = 12 sec, and time (t2) = 11 sec​

• The power to take an object to a certain height in 12 sec by 1^st person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{80gh}{12}\)       ----(1)

• The power to take an object to a certain height in 11 sec by 2^nd person is 

\(\Rightarrow P_1 = \frac{mgh}{t}=\frac{60gh}{11}\)       ----(2)

On dividing equations 1 and 2, we get

\(\Rightarrow \frac{P_1}{P_2} =\frac{\frac{80gh}{12}}{\frac{60gh}{11}}=\frac{11}{9}\)