Biology XI Notes
Chapter # 03
Short Questions Answers
Section II – Unity Of Life
THE ENZYMES
Q.1: What are enzymes and what are the characters of enzymes?
Ans: ENZYMES:
Enzymes are the organic proteinaceous substances which catalyze chemical reactions in the living organisms. These are considered as bio-catalysts. They increase the rate of chemical reaction but are not consumed in the process:
The term enzyme was used by a scientist, Friedrich Wilhelm Kuhn in 1878.
Chapter # 01 - Biology - XI
Short Questions Answers Section I - Introduction
Q.1: What is Biology?
Ans:
Biology is one of the natural sciences, which deals with the study of living organisms. It is known as the study of life. The word "biology" is derived from Greek words "Bios" meaning life and "Logos" meaning study or knowledge.
Formerly, living organisms were classified into two kingdoms:
Plant Kingdom:
In this kingdom, plants were included. The study of plants is called Botany.
Animal Kingdom:
In this kingdom, animals were included. The study of animals is known as Zoology.
Q.1: Explain how you would test whether the radiation from a radioactive source is α, β or Gamma radiation?
Ans: When radiations are allowed to pass through a magnetic field, the α and β particles are deflected while γ-rays pass through undeflected. This technique helps to identify the radiation.
Q.2: A particle which produces more ionization is less penetrating. Why?
Ans: When a particle ionizes an atom, it loses a part of its energy. Since the greater the ionizing power, the greater is the loss of energy; and hence, the smaller is its penetrating power.
Chapter – 19
Q.1: How many neutrons and protons do the following nuclei contain?
| Nuclide | Protons | Neutrons |
|---|---|---|
| 13 | ||
| 18 | ||
| 56 | ||
| 82 | ||
| 14 | ||
| 92 |
Q.2: Do , , and gamma rays come from the same element? Why do we find all three in many radioactive samples?
Ans: A radioactive element either emits -particles or -particles, but never both. Gamma radiations generally accompany -emission and, in some cases, with -emission.
Q.1: The Bohr’s theory of hydrogen atom is based upon several assumptions. Do any of these assumptions contradict classical physics?
Ans: The assumption in Bohr’s theory that an electron moving around the nucleus in a certain orbit does not radiate energy is contrary to classical electrodynamics.
Q.2: Why does the hydrogen gas produced in the laboratory not glow and emit radiations?
Ans: A spectrum is given by the light emitted from an incandescent gas or vapour e.g., electric discharge through a gas or hydrogen-filled discharge tube.
ADVENT OF MODERN PHYSICS
Chapter - 17
Q.1: What do you understand by a frame of reference? What is the difference between inertial frame and non-inertial frame?
Ans: The position and motion of a body can be located with reference to some coordinate system, called the frame of reference.
The frame of reference that is either at rest or moves with uniform velocity is called an inertial frame. It has zero linear or rotational acceleration. Newton’s laws hold well in such a frame. All inertial frames of references are equivalent.
Chapter - 16
Q.1: Under what circumstances does a charge radiate electromagnetic waves?
Ans: A charge radiates electromagnetic (e.m.) waves when it is accelerated.
Q.2: In an electromagnetic wave, what is the relationship, if any, between the variation in the magnetic and electric fields?
Ans: In an electromagnetic wave, the transverse sinusoidal oscillating electric field and magnetic field are propagated at right angles to each other and to the direction of motion.
Chapter - 15
Q.1: What is the function of the concave pole pieces and the coaxial soft iron cylinder in the moving coil galvanometer?
Ans: The concave magnetic poles and the cylindrical core make the magnetic field radial and stronger (so the current becomes directly proportional to the deflection).
Q.2: Why is it necessary to have some form of controlling couple in the moving coil galvanometer?
Ans: Controlling couple is necessary to control the motion of the coil, it is proportional to the current to be measured. It is produced by using a spring control method, which consists of two hair springs attached to a spindle wound in the opposite directions. As the coil rotates the spring winds up and produces a counter torque. The coil comes to rest (the final deflection of the pointer is given) when the deflecting torque (or magnetic torque) is counterbalanced by the controlling torque (or restoring torque).
Chapter – 14
Q.1: What is flux density and how is it related to the number of lines of induction expressed in Webers?
Ans: Magnetic flux density is the magnetic flux per unit area . The unit of flux density is Weber per (or tesla, ). Magnetic flux is the total number of magnetic lines of induction passing perpendicularly through an area . Its SI unit is ‘Weber’ . Hence magnetic flux density refers to the number of lines of induction (in Webers) per square meter.
Q.2: Charged particles fired in a vacuum tube hit a fluorescent screen. Will it be possible to know whether they are positive or negative?
Ans: Yes, the charge on particles in motion can be found by applying a magnetic field perpendicular to the motion of the charges and by observing the deflection. A positive charge in an inward perpendicular magnetic field is deflected upward. In an electric field, a positive charge will be deflected towards the negative side (plate).
Chapter – 13
Q.1: Electrons leave a dry cell and flow through a lamp back to the cell. Which terminal the positive or negative is the one from which electrons leave the cell? In which direction is the conventional current?
Ans: Electrons leave the negative terminal of the cell and move towards the positive terminal. However, as a convention, the conventional current is assumed to be the consisted of positive electric charges moving from a positive terminal to the negative terminal change flowing through the area per unit time (I = q/t).
Q.2: Both p.d. and e.m.f. are measured in volts. What is the difference between these concepts?
Ans: P.d. is the work done per unit charge across resistor in a closed circuit. But e.m.f. the total p.d. across the external and internal resistance, it refers to a source of current and is greater than the potential drop in an external circuit. (e.m.f. p.d. + internal resistance drop)
Chapter – 12
Q.1: Repulsion is the sure test of electrification. Explain?
Ans: Electrostatic attraction is observed between oppositely charged bodies and also between a charged (+ve or -ve) and an uncharged body. But, however, only two charges of the same kind (both +ve or both -ve) can repel each other. Hence, repulsion is the sure test of electrification.
Q.2: Will a solid metal sphere hold a large electric charge than a hollow sphere of the same diameter? Where the charge does resides in each case?
Ans: A solid metal sphere will hold the same amount of charge as is held by a hollow sphere of the same diameter. This is due to the fact that any excess electric charge resides only on the outer surface of a conductor.
Chapter - 11
Q.1: How do you distinguish between temperature and heat? Give example?
Ans: Heat is the energy flowing between bodies and surroundings due to the difference of temperature. But temperature is a measure of the average translation kinetic energy of the molecules of a body. If we dip a red hot iron ball in the sea, heat will flow. The amount of internal energy possessed by the ball is very small as compared to the immense amount contained in the sea.
Q.2: Why is the earth not in thermal equilibrium with the sun?
Ans: The earth is not in thermal equilibrium with the sun; because while the earth is being warmed by the absorbed radiant energy, it is also losing heat in various ways (e.g. re-radiation, conduction, convection and evaporation). Moreover, they are not in perfect thermal contact with each other. The average temperature of the earth is about 300 K.
Q.1: What is Science?
Ans: Science:
The word science refers to the study of a fact by collecting information through observation, presenting it in a mathematical way, justifying the idea with experiment, and finally making a conclusion about the fact.
Q.2: Define Physics.
Ans: Physics:
One of the most basic and ancient sciences is Physics. It can be defined as: Physics is the branch of science which observes the nature, represents it mathematically, and concludes with the experiment.
In other words, Physics is the branch of science that deals with studies of matter, its composition, properties, and interaction with energy.
ENGLISH 10TH - Short Question Answers
UNIT # 8.1
Q.1: What are the main causes of road accidents?
Ans. One of the key reasons for road accidents is over-speeding; the other is the disregard for traffic rules.
Q.2: What two important safety measures can save people’s lives?
Ans. Two important safety measures that can save people’s lives and protect them from disability are wearing helmets and fastening seat belts.
COMPOUND PREPOSITION
TYPE 3 CONDITIONAL SENTENCES
ENGLISH 10TH - Language Practice
UNIT # 7.3
Prepositions
A preposition shows a relation between a word and a noun or a pronoun that follows it.
پری پوزیشن کسی لفظ اور ناؤن کے درمیان تعلق کو ظاہر کرتا ہے۔
The book is on the table.
کتاب میز پر ہے۔
There is milk in the jug.
دودھ جگ میں ہے۔
ENGLISH 10TH - Short Question Answers
UNIT # 7.1
Q.1: Why did Asif's parents decide to take him to the Gorakh Hills for his birthday?
Ans. Asif’s parents decided to take him to the Gorakh Hills for his birthday because they knew his love for travel.
Q.2: What do you know about Gorakh Hills?
Ans. Gorakh Hills Station is situated at an elevation of 5,690 ft. from the sea level and is the highest summit and a holiday resort in Sindh.
REVISION OF DIRECT / INDIRECT QUESTIONS
ENGLISH 10TH - Language Practice
UNIT # 6.3
Transitional Devices Showing Order & Reason
Transitional devices are words or phrases that help carry a thought from one sentence to another, from one idea to another, or from one paragraph to another. They link sentences and paragraphs together so that there are no abrupt jumps or breaks.
ENGLISH 10TH - Short Question Answers
THE VOICE OF GOD
UNIT # 6.1
Q.1: Why should we speak gently to others? What lesson we learn from the poem 'Speak Gently'? OR What does the poet/poetess in the poem 'Speak Gently' tell you?
Ans. The central idea or the message of the beautiful and heart touching poem “Speak Gently” is that speaking harshly hurts the feelings of our fellowmen and makes them unhappy. While speaking gently and using soft words makes them happy. We should speak sweetly and gently. This is the lesson we learn from the poem “Speak Gently”.
MODAL VERBS
ENGLISH 10TH - Language Practice
UNIT # 5.3
Number of Nouns
A Noun that denotes one person or thing, is called Singular Number; as,
boy, cow, bird, book, pen.
A Noun that denotes more than one person or thing, is called Plural Number; as,
boys, cows, birds, books, pens.
UNIT # 5.1
Q.1: How many families were going on the trip?
Ans. Two families were going on the trip. Mr Aziz’s family and his brother Mr Karim’s family were going on the trip.
Q.2: How did Mr Aziz and Mr Karim’s family reach their destination?
Ans. They reached their destination by train.
Q.3: Where was the house that Mr Aziz rented?
Ans. The house was far from the station and near the fields.
