Saved Bookmarks
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 3501. |
Question : Give the full form of: CFCs. UNEP |
| Answer» Solution :CFCS - CHLOROFLUROCARBONS UNEP - United NATIONS Environment PROGRAMME | |
| 3502. |
Question : Give the energy transformation that takes place in the process of photosynthesis. |
| Answer» SOLUTION :Solar ENERGY is converted into CHEMICAL energy during PHOTOSYNTHESIS. | |
| 3503. |
Question : Give the common name of the Hirudinaria granulosa. |
| Answer» SOLUTION :INDIAN CATTLE LEECH. | |
| 3504. |
Question : Give the basic features of the mechanism of inheritance. |
|
Answer» Solution :(i) Characters are controlled by genes. (ii) Each gene controls one character. (iii) There may be two or more forms of gene. (IV) One form may be DOMINANT over the other. (v) Genes are present on chromosomes. (VI) An individual has two forms of gene whether SIMILAR or dissimilar. (VII) The two forms separate at the time of gamete formation. (viii) The two forms are brought together in the zygote. |
|
| 3505. |
Question : Give suitable explanations for each statement given below. Synapses are of different types. |
|
Answer» |
|
| 3506. |
Question : Give suitable explanations for each statement given below. Spinal nerves are mixed nerves. |
|
Answer» |
|
| 3507. |
Question : Give scientific reasons for the following statements: Variation is necessary for the maintenance of existence of any species. |
|
Answer» Solution :Specific species or its POPULATION live in the PARTICULAR environment or HABITAT which is suitable to them. `rarr` There are changes taking place on earth e.g., fluctuation in temperature, variation in the water level, etc. `rarr` Organisms possesing variations get a CHANCE to survive in the changing environment. `rarr` Due to variation, organisms can adapt to the environment and hence they can EXIST through adaptations. `rarr` With the help of variation geographical distribution of organisms increase. Hence, variation is necessary for the maintenance of existence of any species. |
|
| 3508. |
Question : Give scientific reasons for the following statements : Though hydropower is renewable source of energy, it creates certain problems. |
|
Answer» Solution :Hydropower is renewable source of ENERGY because water gets refilled in reservoir during RAINING. `rarr` High-rise dams are constructed to generate hydroelectricity. `rarr` Such dams are constructed in hilly areas causing ENVIRONMENTAL changes. `rarr` Large eco-systems are submerged under water and destroyed. `rarr` The submerged vegetation DECAYING anaerobically releases large amount of greenhouse gas, i.e., methane. `rarr` Large areas of agricultural land is also submerged. MANY natives are thus displaced. `rarr` Rural-tribal human races may lose their habitat. So, Hydropower plant construction creates certain problems. |
|
| 3509. |
Question : Give scientific reasons for the following statements: The use of ultrasound technique should be banned for the sex determination. |
|
Answer» Solution :The ultrasound technique should be USED for detection of genetic and other structural abnormalities in embryo. `rarr` Some people use the ultrasound technique (sonography) illegally for sex determination of embryo. `rarr` Due to preference to male CHILD the female embryo is aborted. `rarr` The killing of the unborn GIRL child is KNOWN as female foeticide. This sex-selective abortion is unethical and illegal. `rarr` By female foeticide, female sex ratio is reducing at an alarming RATE in India. Hence, the use of ultrasound technique should be banned for the prenatal sex determination. |
|
| 3510. |
Question : Give scientific reasons for the following statements: The sex of the children is determined by father. |
|
Answer» Solution :The man produces two TYPES of sperms. `50%` of the sperms produced contain X as a sex chromosome, while the remaining `50%` of the sperms contain Y as a sex chromosome. The WOMAN produces all the ova of only one type, i.e., containing only one X-chromosome as a sex chromosome. A child who inherits an X-chromosome from her father will be a girl and one who inherits a Y-chromosome from him will be a boy. Thus, in human beings, the type of sperm that participates in the process of FERTILISATION, determines the sex of the child. Hence, the sex of the children is determined by father or by the PATERNAL CHROMOSOMES in sperm. |
|
| 3511. |
Question : Give scientific reasons for the following statements: The pea plants (Pisum sativum) were selected for Mendel's experiments. |
| Answer» Solution :(1) They are small plants and can be EASILY grown. (2) They are annual plants. So there are more chances of studying more number of generations every YEAR. (3) It produces a LARGE number of offsprings. (4) Its flowers are bisexual and generally show self-fertilisation. (5) Artificially cross pollination can be done as and when REQUIRED. (6) There are varieties of characters. Each character shows atleast TWO contrasting expressions. | |
| 3512. |
Question : Give scientific reasons for the following statements: The property of vegetative propagation is useful in agricultural purposes. |
|
Answer» Solution :In many plants root, stem and leaves DEVELOP into condition. Such a mode of reproduction is called new plants under appropriate vegetative propagation. Advantages of vegetative propagation are as follow : (1) Vegetative propagation is used in layering or grafting methods to grow many plants like sugarcane, grapes for AGRICULTURAL roses PURPOSES. (2) Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. (3) The plants that have LOST the capacity to produce seeds can also be produced by vegetative propagation. e.g., banana, orange, rose, JASMINE ( 4 ) All plants produced by vegetative propagation are genetically similar to the parent plant. |
|
| 3513. |
Question : Give scientific reasons for the following statements: The offsprings formed through asexual reproduction have same genetic constitution as their parent cell. |
|
Answer» Solution :In asexual reproduction, the union of male and female gametes does not occur. `rarr` SINGLE parent is involved in asexual reproduction. The process of formation of new cell begins with the creation of DNA copies. `rarr` Two offsprings are FORMED from the single parent cell which POSSESS EQUAL proportion of DNA. Hence, the offsprings formed through asexual reproduction have same GENETIC constitution as their parent cell. |
|
| 3514. |
Question : Give scientific reasons for the following statements: The number of bryophyllum keep on increasing in garden. |
|
Answer» Solution :In some plants, parts like root, stem and leaves can give rise to buds in DORMANT state which acts as reproductive unit. `RARR` When suitable moisture and temperature are provided to these dormant structures, they form NEW plants. `rarr` Buds found on the leaves of bryophyllum induce vegetative propagation. `rarr` In garden, the detatched buds germinate under favourable conditions such as moisture, nutrients, suitable temperature. HENCE, the NUMBER of bryophyllum keep on increasing in garden. |
|
| 3515. |
Question : Give scientific reasons for the following statements: The chances of birth of a male child (son) or a female child (daughter) are equal. |
|
Answer» Solution :In HUMAN beings, the sex of the child is determined by the FATHER. The father produces two types of sperms. Both the types of sperms are produced equally in number. `50%` of the total sperms produced CONTAIN X-sex chromosome. While the remaining `50%` of sperms produced contain Y-sex chromosome along with autosomes. The chances of each type of sperm to fertilise the OVUM are therefore equal. Hence, the chances of birth of a SON or a daughter are equal. |
|
| 3516. |
Question : Give scientific reasons for the following statements: The characters are under the control of genes. |
| Answer» Solution :A gene is the unit of heredity. It is a segment of DNA of specific LENGTH, arranged sequentially along the length of the chromosome. Each gene is functionally specific and synthesizes a specific TYPE of protein. The enzymes are all proteins and these proteins (as enzymes) for the species because adaptation causes survival of species induce specific biochemical process. The substances or proteins, formed during these processes, are responsible for the expression of characters. HENCE, the characters are under the CONTROL of genes. | |
| 3517. |
Question : Give scientific reasons for the following statements: Testes are situated outside the abdominal cavity. |
|
Answer» SOLUTION :Sperms are reduced by the testis. `RARR` The TEMPERATURE of testis remains `2-3^(@)C` LOWER than the body temperature which is optimal for the formation of sperms. `rarr` If testis remain in abdominal cavity, then at the higher temperature, testes are unable to produce sperms. Hence, testes are situated OUTSIDE the abdominal cavity. |
|
| 3518. |
Question : Give scientific reasons for the following statements: Sometimes in the earth's crust the imprint of the entire body or the organs are maintained. |
|
Answer» Solution :The DEAD bodies of PLANTS or animals, in presence of OXYGEN and MOISTURE, UNDERGO decomposition with the help of microorganisms. But sometimes in certain environmental conditions their bodies or organs do not get decomposed fully. The dead body may be entangled in mud and the same may be covered by dry stony covering. This prevents the dead body to decompose further. The mud settles around the dead body or organ in the shape of the later, and form stony covering. In this stony covering the imprint of the body or the organ is formed as a fossil. That is why, sometimes in the earth.s crust the imprint of the dead body or the organs are maintained. |
|
| 3519. |
Question : Give scientific reasons for the following statements: Sexual reproduction gives rise to variations. |
|
Answer» SOLUTION :Two PARENTS are involved in sexual REPRODUCTION. The offspring inherits the genetic material (DNA) from both the parents through the gametes. Gametes are produced by meiosis. NEW combinations and new arrangement of genes are formed as a result of meiosis. These new combinations of genes on the chromosomes generate one or more variations in the ZYGOTE that inherits into an offspring. Hence sexual reproduction creates more variations. |
|
| 3520. |
Question : Give scientific reasons for the following statements: Response to stimuli is the characteristic of every living organism. |
|
Answer» Solution :All living organisms experience the effects of changes in the atmosphere that SURROUNDS them and tend to respond differently against them. The living organisms show a SLOW or rapid response to stimuli such as heat, cold, sound, touch, pressure, etc. Responses are expressed against these stimuli through hormones in plants and nervous system as well as hormones in animals. e.g., The plants BEND in the direction of light. Man shows shivering effect in severe cold and perspiration in HOT season. THUS, the response to stimuli the characteristic of every living organisms. |
|
| 3521. |
Question : Give scientific reasons for the following statements: It is not true that human beings have evolved from chimpanzees. |
|
Answer» SOLUTION :Both human beings and chimpanzees had a common ancestor a long time ago. This common ancestor is likely to have been neither human or chimpanzee. The FIRST step of separation from that ancestor is unlikely to have resulted in modern chimpanzees and human beings. INSTEAD, the two resultant species have PROBABLY evolved in their own separate ways to give rise to the current forms. That is why, it is not true that human beings have evolved from chimpanzees. |
|
| 3522. |
Question : Give scientific reasons for the following statements: Prenatal determination sex has been prohibited by law. |
|
Answer» Solution :The ultrasound technique should be used for detection of genetic and other structural abnormalities in embryo. `rarr` Some people USE the ultrasound technique (sonography) illegally for SEX determination of embryo. `rarr` Due to PREFERENCE to male CHILD the female embryo is aborted. `rarr` The killing of the UNBORN girl child is known as female foeticide. This sex-selective abortion is unethical and illegal. `rarr` By female foeticide, female sex ratio is reducing at an alarming rate in India. Hence, the use of ultrasound technique should be banned for the prenatal sex determination. |
|
| 3523. |
Question : Give scientific reasons for the following statements : From environmental point of view, we should reduce the use of fossil fuels. |
|
Answer» Solution :The fossil fuels are non-renewable source of energy and in limited reserves. `rarr` The growing DEMAND for energy at global level are largely meet by fossil fuels. `rarr` Excessive burning of fossil fuels - coal and PETROLEUM increases the level of air pollution. e.g., CARBON dioxide, sulphur dioxide and OXIDES of nitrogen are released in excess in atmosphere causing such air pollution. `rarr` Carbon dioxide is a main greenhouse gas that causes global warming. `rarr` Sulphur dioxide and oxides of nitrogen lead to acid rain which affects water and soil resources. So, reduce the adverse EFFECTS on environment, we should reduce the use of fossil fuels. |
|
| 3524. |
Question : Give scientific reasons for the following statements : Few simple steps should be helpful to conserve energy resources. |
|
Answer» Solution :(1) Switch off the lights, fans, television and other electrical appliances when not in use. (2) Make use of stairs INSTEAD of lift at least up to two to three floors in a building. ( 3 ) Pressure cookers should be used to save the fuels. ( 4 ) Bicycles can be used to cover short distances, (5) Public TRANSPORT SYSTEM (local buses and TRAINS) in the cities should be made available so PEOPLE do not use their own vehicles to commute. By such simple steps, we can save electricity and fossil fuels. |
|
| 3525. |
Question : Give scientific reasons for the following statements: Extinction of species can be prevented in sexually reproducting organisms. |
|
Answer» Solution :In sexual reproduction, a zygote is formed by the union of sexual reproductive cells through fertilisation. `rarr` The male reproductive cell is formed in father.s body and female reproductive cell is formed in mother.s body. `rarr` THUS, offspring gets genetic material (DNA) of two different parents. So, there is variation in offspring. `rarr` This variation HELPS the individual to GET adapted to the changing environment. So, organism can live better. `rarr` Through variation and ADAPTATION, species extinction can be prevented and continuity of life is maintained. So, extinction of species can be prevented in sexually reproducting organisms. |
|
| 3526. |
Question : Give scientific reasons for the following statements: Contraceptive pills are helpful to prevent pregnancy. |
|
Answer» SOLUTION :Pills used contraception form contraceptive chemical METHOD. `RARR` The female USES oral contraceptive pills. `rarr` The oral pills contain a combination of hormones (progesterone) which stop the release of eggs and fertilisation cannot OCCUR. `rarr` By using, such pills fertilisation can be prevented. Hence, contraceptive pills are helpful to prevent pregnancy. |
|
| 3527. |
Question : Give scientific reasons for the following statements: Each new generation through sexual mode of reproduction will end up in equal number of chromosomes and the DNA content instead of double to its parents. |
|
Answer» Solution :In SEXUAL mode of reproduction, each NEW generation is the combination of the DNA copies from two parents. Each new generation gets twice the amount of DNA compared to that with the previous generation. But reduction division i.e., meiosis occurs during gamete formation. As a result germ CELLS have HALF the number of chromosomes and half the amount of DNA set as compared to the non- reproductive body cells. When haploid germ cells from two parents fuse during sexual reproduction, it results in diploid zygote. Chromosomes and the DNA content in new generation is thus reestablished. |
|
| 3528. |
Question : Give reasons why (Do any three out of four):(i) Herbivores have longer small intestine as compared tocarnivores.(ii)Mucus is secreted along with hydrochloricacid in the stomach.(iii)Rings of cartilage are present in trachea.(iv)Lungs always contain a residual volumeof air . |
|
Answer» Solution :(i) Herbivores have ionger SMALLINTESTINE so as to facilitatedigestion of cellulose. (ii)Mucus is secretedalongwith HCI so as to protect theinner liningof stomach from excoriation. (iii)Incomplete C-shaped RINGS of cartilagepresentin TRACHEA ensures that the air PASSAGE doesnot collapsewhenthere is no airin it. (iv)Lungs alwayscontain a residual volumeof air to provide sufficient `O_(2)`to be absorbed and`CO_(2)`to be RELEASED. |
|
| 3529. |
Question : Give reasons why acquired characters are not inherited. NCERT Exemplar |
| Answer» Solution :An individual cannot pass on its experiences of its lifetime to its progeny. These experiences do not bring in any change in the reproductive tissue of the individual. Change in nonreproductive tissues cannot be passed on to the DNA of the germ CELLS. HENCE acquired characters cannot direct EVOLUTION. | |
| 3530. |
Question : Give reasons: (i) Plants look green. (ii) The respiratory surface of earthworm is its skin. (iii) Nutrition is necessary for an organism. (iv) We boil the leaf in alcohol when we are testing it for starch. |
|
Answer» Solution :(i) The leaves of plants contain green pigments called CHLOROPHYLL which is necessary for photosynthesis. Plants reflect green tight of sunlight, so they LOOK green. (ii) The skin of earthworm is quite thin and moist and has rich blood supply. So, it RESPIRES through its skin. (iii) An organism requires NUTRIENTS like carbohydrates, FATS, proteins, minerals and vitamins for the growth, reproduction and metabolic activities, so nutrition is necessary for an organism. (iv) We boil the leaf in alcohol to remove chlorophyll from green leaf. |
|
| 3531. |
Question : Give reasons : i) lonic compounds in solid state do not conduet electricity, whereas in molten state are good conductors of electricity. (ii) ii) Silver articles when exposed to air gradually turn blackish. ii) Chenmical reaction does not take place when copper is added to iron sulphate solution. |
|
Answer» SOLUTION :(i) In the solid state ionic compounds do not conduct electricity because movement of ions in the solid is not possible due to their RIGID structure. In solid state, they are hard because of the strong force of attraction between the positive and negative ions. In MOLTEN state, electrostatic forces of attraction between the oppositely charged ions are overcome due to the heat. thus the ions nnove freely and conduct electricity. (II) Silver reaucts with sulphur in the air to fornm a coating of silver sulphide. Reactivity of copper is less than that of iron. |
|
| 3532. |
Question : Stomata open at night and close during the day time in |
| Answer» Solution :Desert plants TAKE up carbon DIOXIDE at NIGHT and prepare an intermediate COMPOUND which is ACTED upon by the energy and absorbed by the chlorophyll during the day. | |
| 3533. |
Question : Give reasons for the following :(i)The muscular walls of ventricles are thicker than the walls ofatria.(ii)Arteries have thick elastic walls.(iii)Veins have valves . |
|
Answer» Solution :(i) The walls of VENTRICLES are thick and muscular as compared to the walls of atria as they are required to pump blood to VARIOUS organs. Right VENTRICLE sends deoxygenated blood to lungs throughpulmonary artery whereas left ventricle sends oxygenated blood to all PARTS of the body through aorta. (ii) Since the blood emerges from the heart under high pressure , the arteries have thick, elastic walls. (iii)Veins have valves to ENSURE that the blood does not flow backward when the atria or ventricles contract. |
|
| 3534. |
Question : Give reasons for the appearance of new combinations of characters in the F_2 progeny. |
| Answer» Solution :During the cross between two true breeding parents (RRYY and rrYY), the RESULTANT OFFSPRING (F1) is heterozygous for the dominant trait. The recessive traits remain masked by the dominant trait in heterozygous CONDITION, Eg: RrYy. When the Fl offsprings are let to self FERTILIZE, they give rise to new combinations as the recessive traits reappear in homozygous CONDITIONS in some of the F2 offsprings. Eg: Rryy, ryy. | |
| 3535. |
Question : Give reasons for the appearance of new combinations of characters in the F_2 progeny. |
| Answer» SOLUTION :The tall/short and round/wrinkled SEED TRAIT are INDEPENDENTLY INHERITED. | |
| 3536. |
Question : Give reason : Wind acts as pollinating agent. |
| Answer» Solution :Wind TRANSPORTS pollen from ANTHER to stigma of ANOTHER flower. | |
| 3537. |
Question :Give reason : Variation is beneficial to a species. |
| Answer» SOLUTION :Variation results in NEW combinations of characters. Hence, it HELPS in EVOLUTION and survival of organism due to better adaptability. | |
| 3538. |
Question : Give reason Uterine linings are thick and spongy. |
| Answer» Solution :Uterine linings are thick and SPONGY to provide protection and nutrition to embryo during its GROWTH and development in the UTERUS. | |
| 3539. |
Question : Give reason : Use of condoms prevents pregnancy. |
| Answer» Solution :Condoms PREVENT entry of SPERM in vagina, thereby PREVENTING fertilisation. | |
| 3540. |
Question : Give reason : Placenta is extremely essential for foetal development. |
| Answer» Solution :Placenta is the CONNECTION between maternal blood and growing FOETUS. It provides it NUTRITION, respiratory gases, REMOVAL of its wastes etc. | |
| 3541. |
Question : Give reason Placenta has villi on embryo's side. |
| Answer» SOLUTION : PLACENTA has villi to PROVIDE large surface area for GLUCOSE and oxygen to PASS through to embryo. | |
| 3542. |
Question :Give reason : Male-female ratio has been disturbed. |
| Answer» Solution : Indiscriminate female foeticide, as GIRLS are considered BURDEN on PARENTS in some societies has resulted in disturbed MALE : female ratio. | |
| 3543. |
Question : Give reason Oral pills are hormonal preparations. |
| Answer» Solution :ORAL pills are HORMONAL preparations - to PREVENT OVULATION and hence fertlisation. | |
| 3544. |
Question :Give reason :Insects act as pollinating |
| Answer» Solution :Insects help in TRANSFER of POLLEN grains from anther to sigma while VISITING flowers for NECTAR. | |
| 3545. |
Question : Give reason :(i)Fine hair and mucusare present in the nasal passage. (ii)Rings of cartilage are present in the throat . |
|
Answer» Solution :(i) Fine hairand mucus are PRESENTIN thenasal passage so that any DUST particles, pathogens etc., can be trapped in here and only clean AIR will enterthe lungs. This is one of the defencemechanism of our body. (ii)Rings of cartilage are presentin the throat in thethroat so that the tracheadoes not collapseon RESPIRATION. |
|
| 3546. |
Question : Give reason for the statement- Since the ovary releases one egg every month, the uterus also prepares itself every month by making its lining thick and spongy. |
| Answer» SOLUTION : The lining of UTERUS becomes thick for nourishing the embryo if fertilisation takes PLACE and EGG REACHES the uterus. | |
| 3547. |
Question : Give reason for the following: a) Metals are regarded as electropositive elements. b) When a piece of copper metal is added to a solution of Zinc sulphate, no change take place, but the blue colour of copper sulphate fades away when a piece of zinc is placed in its solution .c) Articles of aluminium do not corrode even though alluminium is an active metal. |
|
Answer» Solution :a) Metals have a tendency to lose one or more electrons to form positive ions. Therefore, metals are called ELECTROPOSITIVE elements. Copper is less reactive than Zinc. Therefore, if cannot displace Zinc from `ZnSO_4`solution. But Zinc being more reactive than copper, it DISPLACES copper from `CuSO_4` solution. As a result the concentration of `Cu^(2+)`ions fall and blue colour fades. ` ZN(s) + underset("blue")(CuSO_4(aq) )to underset("colourless")(ZnSO_4 (aq) ) + Cu(s)` C) Aluminium being a reactive metal readily combines with oxygen to give a PROTECTIVE layer of `AI_2O_3`. As a result further corrosion stops. |
|
| 3548. |
Question : Give reason : Blocking vas deferens prevents pregnancy. |
| Answer» Solution :By blocking vas deferens, the SPERMS do not get PASSAGE to MOVE out, THUS no fertilisation. | |
| 3549. |
Question : Give reason : Blocking of fallopian tubes prevents pregnancy. |
| Answer» Solution :By BLOCKING fallopian TUBE, the EGG is not carried out, sperms do not reach it, so no FERTILISATION. | |