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4701.

Question : A particular species ‘X’ has more characteristics with species 'Y', whereas another species 'Z' has less common characteristics with species 'Y'. Which two species are more closely related? Why? On what basis are the eukaryotic organisms further classified? Why is this basis important? What is the importance of homologous organs?

Answer»

Solution :Species .X. is more closely related with species .Y..
The more closely related species will have more characteristics in common. Hence species X and Y are closely related.
Eukaryotic organisms are further classified on the basis of whether they are unicellular or multi- cellular.
This basis marks a very fundamental DIFFERENCE in body design, because of SPECIALISATION of CELL types and tissues.
Homologous ORGANS help to identify an evolutionary RELATIONSHIP between apparently different species.
Discussion
4702.

Question : A partially permeable membrane of a cell facilitates the process of

Answer»

DIFFUSION
plasmolysis
osmosis
imbibition

ANSWER :C
Discussion
4703.

Question : A palaeontologist observes the jaw of an animal and concludes that it belong to mammals. Give reason for his conclusion.

Answer»

SOLUTION :TEETH are of different types (heterodont) embedded in sockets in jaw BONES (thecodont)
Discussion
4704.

Question : a) Oil and fat containing food items are flushed with nitrogen. Why? b) Write the balanced chemcial equations for the following reactions. i) Calcium hydroxide + Carbondioxide to Calcium carbonate + water ii) zinc + Silver nitrate to Zic nitrate + silver iii) Aluminium + copper chloride to Aluminium chloride + Copper

Answer»

Solution :To prevent the oxidation of oil and fat present in food items. nitrogen gas is flushed in food packets products formed due to oxidation of oil and fat have unpleasant smell and taste due to rancidity. Flushing food items CONTAINING .fat and oil with nitrogen PREVENTS rancidity.
B) i) `Ca(OH)_(2(aq))+ CO_(2(g)) to CaCO_(3(s)) + H_2 O_((l))`
II) `Zn_((s)) - 2AgNO_3 to Zn(NO_3)_(2(aq)) + 2Ag_((s))`
iii) `2Al_((s)) + 2CuCl_(2(aq)) to 2AlCl_(3(aq)) + 3Cu`
Discussion
4705.

Question : A normal man respires in a minute

Answer»

10-15 TIMES
14-18 times
20-25 times
25–30 times 

ANSWER :B
Discussion
4706.

Question : A new drug developed for diabetes is from,

Answer»

Dog
Platypus
Cat
Horse

Answer :B
Discussion
4707.

Question : A neuron contains all cell organelles except_____

Answer»

SOLUTION :GOLGI APPARATUS in AXON
Discussion
4708.

Question : A nerve input signal travelled only upto the spinal cord and gave output signal for a response. What type of action will the body show - voluntary or involuntary ?

Answer»

SOLUTION :INVOLUNTARY ACTIONS.
Discussion
4709.

Question : A nerve cell differs from a muscle cell in

Answer»

genetic constitution
the KINDS of proteins in the cytoplasm
being noncontractile
the features STATED in (B) and (c )

ANSWER :B
Discussion
4710.

Question : A nephridium of an eathworm drains materials directly from the

Answer»

gut
coelom
lymph
blood

Answer :B
Discussion
4711.

Question : A natural occurring class of plant hormones cytokinins has been found to help increase cotton yields during drought conditions. It has been observed that young cotton seedlings have small root system, making it difficult for them to reach available soil water. Cytokinins assists the young plants in water stress defences, promoting the plant to quickly build a bigger root system to access deep soil mosture. To be effective this phytohormone should be at an early stage of development."Plant hormones help to co - ordinate growth."Justify the statement by giving three examples.

Answer»

Solution :Examples:
(a) AUXINS play a role in the DEVELOPMENT of seedless fruits.
(B) Gibberellin stimulates STEM elongation.
(c ) Abscisic ACID inhibits growth.
Discussion
4712.

Question : A natural occurring class of plant hormones cytokinins has been found to help increase cotton yields during drought conditions. It has been observed that young cotton seedlings have small root system, making it difficult for them to reach available soil water. Cytokinins assists the young plants in water stress defences, promoting the plant to quickly build a bigger root system to access deep soil mosture. To be effective this phytohormone should be at an early stage of development. Which hormone is synthesized at the shoot - tip of plant body ?

Answer»

Solution :AUXIN is SYNTHESIZED at the shoot - TIP of plant BDOY.
Discussion
4713.

Question : A natural occurring class of plant hormones cytokinins has been found to help increase cotton yields during drought conditions. It has been observed that young cotton seedlings have small root system, making it difficult for them to reach available soil water. Cytokinins assists the young plants in water stress defenses, promoting the plant to quickly build a bigger root system to access deep soil moisture. To be effective this phytohormone should be at an early stage of development. What are phytohormones ?

Answer»

SOLUTION :PLANT HORMONES are KNOWN as PHYTOHORMONES.
Discussion
4714.

Question : (a) Name two sexually transmitted diseases. (b) Why prenatal sex determination is prohibited by law? (c) What are the different methods of contraception?

Answer»

Solution :(a) AIDS, Syphilis.
(b) Surgery can be used to prevent frequent or unwanted pregnancies. However, this METHOD can be used by people for GENDER-selective abortion as happens in illegal female foeticides. As a result of prenatal gender determination, the child-gender ratio is declining at an ALARMING rate in our societies.
Therefore, prenatal gender-determination has been prohibited by law.
(c) (i) Creating a mechanical BARRIER so that the sperms do not reach the egg. This is done with a CONDOM which is worn around the penis or a similar device that is placed in the vagina.
(ii) Changing the hormonal balance of the body so that fertilization cannot occur. This is done with the help of oral contraceptive pills.
(iii) Contraceptive devices like loop or copper-T are placed in the uterus to prevent pregnancy.
(iv) Surgical methods like vasectomy in males and tubectomy in females.
Discussion
4715.

Question : (i) Write the electron dot structure for sodium, oxygen and magnesium. (ii) Show the formation of Na_(2)O and MgO by the transfer of electrons. (iii) What are the ions present in these compounds.

Answer»

Solution :(a) Magnesium and Manganese
(b) Formation LOSES twon electrons , and forms Magnesium ions to complete its OCTET.
`Mg rarr Mf^(2+) +2^( e )`
OXYGEN gains that two electrons to becomes `o^(2-)`
`Mg^(2+) +O_(2) rarr MgO`
Discussion
4716.

Question : (a) Name the respective part of human female reproductive system: (i) that produces eggs, (ii) where fusion of eggs and sperm takes place. (b) Describe in brief what happens to the zygote after it gets implanted.

Answer»

Solution :(a) (i) Ovary (ii) Fallopian TUBE (B) The zygote formed after fertilisation in the fallopian tube is implanted in the uterus: It divides repeatedly to form a mass of cells known as embryo. This embryo gets attached to the inner LAYER of the uterine cavity, i.e., endometrium. It thickens every month and is supplied with BLOOD to nourish the embryo. Soon it gets covered by rapidly dividing uterine cells. This leads to pregnancy.
Within a span of some months, the embryo starts developing limbs and begins to resemble a miniature human being. When all body parts of the embryo can be RECOGNISED, it becomes a foetus. When this foetus is fully developed, the mother gives birth to the baby.
Discussion
4717.

Question : (a) Name the respective part of human female reproductive system. (i) that produces egg. (ii) where fusion of egg and sperm takes place, and (iii) where zygote gets implanted. (b) Describe in brief what happens to the zygote after it gets implanted.

Answer»

SOLUTION : (a) (i) Ovary
(ii) FALLOPIAN tube
(iii) Uterus
(b) As soon as zygote is implanted it starts dividing. It travels to the uterus, where it GETS implanted. The embryo gets nutrition from mother.s blood with the help placenta. This provides surface area for exchange of glucose and oxygen to go to embryo and REMOVAL of wastes from it.
Discussion
4718.

Question : (a) Name the structure in human male reproductive system that delivers the sperms from the testes to the urethra. (b) Name the structure in human female reproductive system which delivers the egg from the ovary to the uterus.

Answer»

Solution :(a) Vas-deferens delivers the SPERMS from the testis to the URETHRA.
(B) The EGG is transferred through fallopian TUBE from ovary to uterus.
Discussion
4719.

Question : (a) Name the raw materials required for photosynthesis. How do plants obtain these raw materials? (b) What are the various conditions necessary for photosynthesis ? (c) Name the various factors which affect the rate of photosynthesis in plants

Answer»
Discussion
4720.

Question : (a) Name the process and explain the type of nutritio found in green plants. List the raw materials required for this process. Give chemical equation for the mentioned process.(b)Write three events that occur during this process.

Answer»

Solution :(a) The process of nutrition in green plants is Photosynthesis.
The type of nutrition is autotrophicnutrition. Autotrophic nutrition requires sunlight, chlorophyll, water andcarbon dioxide.
Plants prepare their own food in the form of glucose which gets CONVERTED to starch. Thisis done USING `CO_(2) and H_(2) O`which gets fixed using energy from sunlight by the chlorophyll molecule presentin green plants.
Equation -
`6CO_(2)+12H_(2)Ooverset("Chlorophyll,Sunlight")to underset(("Glucose"))(C_(6)H_(12)O_(6))+6O_(2)+6H_(2)O`
(b)The three events involved are :
(i) Absorption of sunlightby chlorophyll.
(II) Conversion of this light energy into chemical and splitting of water into `H^(+) and OH^(-)`using this energy.
(iii)Reduction of `CO_(2)`to carbohydrateby `H^(+)` produced due to splitting of water .
Discussion
4721.

Question :Explain the principles of Lamarckian theory.

Answer»

SOLUTION :(a) Lamarckism is the hypothesis that an orgganism can pass on characteristics, that it has acquired through use or disuse, during it.s LIFETIME to the offspring. Lamarck.s theory of evolution was published in .Philosophic Zoologique. in the year 1809.
Lamarckism is popularly KNOWN as .Theory of inheritance of Acquired Characters.. or ..Use and Disuse theory..
(b) (i) Internal vital force :
Due to the inherent ability of the living organisms or their component parts tend to increase in size continuosly.
(ii) Environment and new needs :
A change in the environment brings about CHANGES in the need of the organisms. In response to the changing environment, the organisms develop cartain adaptive characters. The adaptations may be in the FORM of develoopment of new parts of body.
(ii) Use and disuse theory :
Lamarck.s use and disuse theory states that, if an organ is used constantly the organ develops well and gets strengthendes. When an organ is not used for a long time, it gradually degenerates The ancestors of Giraffe were provided with short neck and short forelimbs. Due to shortage of grass, they are forced to feed on leaves from trees. The continuous strtching of their neck and forelimbs, resulted in the development of long neck and long forelimbs, which is an example for constant use of an organ. The degenerated wing Kiwi is an example for organ of tisuse.
(iv). Theory of Inheritance of acquired characters :
Animals respond to the changes, When is a change When there is a change in the environment. The develop adaptive structures. The characters, developed during their life, in response to the environment changes are called acquired characters. The acquired characters are transmitted to the offspring by the process of inhertance.
Discussion
4722.

Question : a] Name the parts of the human female reproductive system where i] fertilisation takes place, ii] implantation of the fertilised egg occurs. b] Explain how the embryo gets nourishment inside the mother's body. c] Write the function of following parts in human female reproductive system: i] Ovary ii] Oviduct iii] Uterus d] Describe in brief the structure and function of placenta. OR Explain the structure and important role of placenta during gestation period of woman.

Answer»

Solution :a] i] oviduct ii] uterus
b] The embryo gets nutrition from the mother.s blood with the help of a special tissue called placenta.
c] i] Ovary: It produces egg (ovum). It also produces the hormones - oestrogen and progesterone.
ii] Oviduct: It is the site of fertilization. It carries egg (ovum) or fertilized ovum (zygote) to the uterus.
iii] Uterus: It is the site of development of embryo. It protects and nourishes the embryo.
d] Placenta: It is a DISC EMBEDDED in uterine wall which contains villi on the embryo side of the tissue and blood space on mother side.
Function of placenta: Placenta functions as a site of exchange of materials between the blood of mother and foetus. It provides a LARGE surface area for glucose and oxygen to pass from the mother to the baby. The foetus gives away WASTE products and carbon DIOXIDE to the mother.s blood for excretion.
Discussion
4723.

Question : Name the parts A, B and C shown in the diagram and write their functions.

Answer»

SOLUTION :(a) In the given figure,
A-represents the pollen grain
B-represents the pollen tube
C-represents the OVULE
D-represents the male gamete

(b) The transfer of pollen grains from the anther to the stigma of a flower is known as pollination.
Significance of pollination:
(i) It is a significant event because it precedes FERTILIZATION.
(ii) It brings the male and female gametes closer for the process of fertilization.
(iii) Cross-pollination INTRODUCES variations in plants because of the mixing of different genes. These variations further increase the adaptability of plants towards the environment or surroundings.
(c) Double fertilization is a characteristic feature of flowering plants. In this process, out of the two sperm nuclei, one sperm nucleus fuses with the egg nucleus to form an embryo (process is called syngamy) and another fuses with the polar nucleus to form an ENDOSPERM (process is called triple fusion). Because two kinds of fusion-syngamy and triple fusion-take place, the process is known as double fertilisation. After fertilisation,
(i) the ovule develops into a seed
(ii) the ovary develops into a fruit
Discussion
4724.

Question : (a) Name the method by which bread mould (Rhizopus fungus) reproduces. Is this method sexaul or asexual? (b) What isyeast? Describe the process of reproduction in yeast with the help of labelled diagrams. (c) Name or tiny fresh-water animal which reproduces by the same method as that of yeast? What is this method known as ? (d) Name two marine organisms which also reproduce by the same method yeast but from colonies.

Answer»


SOLUTION :N//A
Discussion
4725.

Question : a] Name the mode of reproduction in following organisms and state important feature of each mode. i] planaria ii] hydra iii] rhizopus b] We can develop new plants from the leaves of Bryophyllum. Comment. c) List two advantages of vegetative propogation over other modes of reproduction.

Answer»

Solution :a] i] Planaria: Fragmentation- occurs when an organism literally BREAKS off from itself. The broken fragments of the organism grow into individual separate organisms.
ii] Hydra-budding: In hydra, a BUD develops as an outgrowth due to repeated cell division at one specific site. These buds develop into tiny individuals and, when fully mature, detach from the parent body and become new independent individuals.
iii] Rhizopus: spore formation occurs when a plant produces tiny spores and propagates through them. It burst open under favourable conditions giving rise to new individual.
b] Occurs asexually through vegetative propagation by leaves. These buds arise at the margins of leaves giving rise to adventitious roots, shoots and small leaves. Thenew PLANTS then detach from the leaves and develop into a mature plant after coming in contact with the soil.
c] i] offspring are clones of their parent plants.
ii] The plants that cannot produce VIABLE seeds such as banana, seedless grapes and oranges, etc, can be easily grown by vegetative propagation.
iii] It is an easier, less expensive and a rapid method of propagation.
Discussion
4726.

Question : (a) Name the main two components of blood. (b) What does plasma contain?

Answer»

SOLUTION :1. The fluid plasma
2. Formed elements (blood cells)
(a) RBC (6) WBC (c) Blood PLATELETS
(B) Plasma is slightly alkaline, containing non-cellular substance, constitute 55% of the blood Organic substances like Proteins, Glucose, Urea, Enzymes, Hormones, Vitamins and Minerals are present in the Plasma.
Discussion
4727.

Question : (a) Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone. (b) Name the parts of the human female reproductive system where- (i) Fertilisation takes place (ii) Implantation of the fertilised egg occurs. (c) Explain how the embryo gets nourishment inside the mother's body.

Answer»

Solution :(a) Testes are the oval-shaped primary reproductive organs in man. Its function is to PRODUCE sperm and MALE SEX hormone called testosterone.
Testosterone hormone INITIATES the development of SECONDARY sexual characters in male
(b) (i) Oviduct
(ii) Uterus.
(c) Refer to Topic-3 Q.8
Discussion
4728.

Question :Name the hormone secreted by an endocrine gland during emergency?

Answer»

Solution : a) Adernalin hormone is secreted by the adrenal gland. It helps to regulate heartbeat, blood PRESSURE, metabolism in the times of strees or emergency to cope up with the SITUATION.
b) Nervous system :
* It consists of nerve impules between PNS, CNS and brain
* The axone and dendrite transmit through a coordinated effort.
* The flow of information is RAPID and the response is quick
* Nerve impulses are not specific in their action.
* Effects are short level.
Hormonal system
* It consists of ENDOCRINE system which secrete hormones directly into blood.
* The information is transmitted or transported through blood.
* The information travels slowly and the response is slow.
* Each bormone has specific action
* It has PROLONGED effects.
Discussion
4729.

Question : (a) Name the gaseous plant hormone. Describe its three different actions in plants. (b) Which hormone is known as stress hormone in plants ? Why?

Answer»

Solution :(a) Ethylene is a gaseous plant hormone. It is a growth inhibitor. The DIFFERENT actions of ethylene are as FOLLOWS:
(i ) Ethylene promotes the ripening of fruits, eg. Tomato, Apple, Mango, Banana and etc.
(ii) Ethylene inhibits the elongation of stem and root in dicots.
(III) Ethylene hastens the senescence of leaves and flowers.
(iv) Ethylene stimulates formation of Abscission zone in leaves, flowers and fruits. This leadsto premature shedding.
(v) Ethylene BREAKS the dormancy of buds, seeds and storage organs.
(b) Abscisic acid (ABA) is a growth inhibitor which regulates abscission and dormancy. It increases tolerance of plants to various kinds of stress. So, it is ALSO called as stress hormone.
Discussion
4730.

Question : (a) Name the following: (i) Thread like non-reproductive structures present in Rhizopus. (ii) 'Blobs' that develop at the tips of the non-reproductive threads in Rhizopus. (b) Explain how these structures protect themselves and what is the function of the structures released from the 'blobs' in Rhizopus.

Answer»

Solution :(a)(i) Hyphae/mycelium, (ii) Sporangia
(B) These structures are protected by thick walls. These structures germinate into new INDIVIDUALS under FAVOURABLE CONDITIONS.
Discussion
4731.

Question : a) Name the gas released at anode during chlor - alkali process and mention the uses of this gas. b) Which gas is released when sodium carbonate reacts with hydrochloric acid? How do you test this gas? Write the word equation for this reaction.

Answer»

Solution : (a) CHLORINE GAS is released at anode during chloro-alkali process.
Uses :
It is used in water treatment.
Manufacture of PVC.
Used as disinfectants and pesticides.
Used in swimming pools, CFC.s etc.
(b)Carbon dioxide `(CO_2) ` gas is evolved when sodium carbonate reacts with hydrochloric acid. When the gas is PASSED through lime water it turns milky (showing that it is carbon dioxide) due to the formation of insoluble calcium carbonate.
METAL carbonate / Metal hydrogen carbonate + Acid `to`Salt + CARBONDIOXIDE + Water.
Discussion
4732.

Question : (a) Name the following : (i) Thread like non-reproductive structures present in Rhizopus. (ii) 'Blobs' that develop at the tips of the non- reproductive threads in Rhizopus. (b) Explain how these structures protect themselves and what is the function of the structures released from the 'blobs' in Rhizopus.

Answer»

Solution :(a) (i) Hyphae
(II) SPORANGIA.
(b) Each sporangium contains hundreds of black-spots and these spores are dispersed into air to germinate on suitable substrate.
Spores have an outer thick wall that PROTECTS them in adverse conditions until they COME in contact with another moist surface and begin to grow.
Function They germinate into new individuals under FAVOURABLE conditions.
Discussion
4733.

Question : (a)Name the following :(i)The three carbon molecule that is formed due to break-down of glucose during respiration.(ii) The nitrogenous waste that is removed from the blood in our kidneys .(b)How do unicellular organisms generally remove waste ?

Answer»

SOLUTION :a (i) PYRUVIC Acid/Pyruvate
(ii)Urea
(b)The undigested food material in the vacuole reaches the rear END ofthe ORGANISM and is thrown outby the process ofexocytosis. Themembrance of the vesicle fuses with the surface membrane .
Discussion
4734.

Question : (a) Name and state the law given by Lindeman which tells us how much energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level. (b) How much energy will be available to hawks in the food chain comprising hawk, snake, paddy and mice, if 10,000 J of energy is available to paddy from the sun ?

Answer»


ANSWER :(B) 0.1 J
Discussion
4735.

Question : (a) Name an organism in which binary fission occurs in a definite orientation (b) Draw a neat diagram of a germinating seed and label on it the following: Cotyledon, Plumule, Radicle.

Answer»

SOLUTION :(a) LEISHMANIA
(B)
Discussion
4736.

Question : A muscle cell is

Answer»

A PROVIDED with an end bulb
SHEATHED
myelinated
CONTRACTILE

ANSWER :D
Discussion
4737.

Question : A motorcycle rider without helmet met an accedent and suffered a spinal cord injury. In this case which signals will get disrupted and why ?

Answer»

Solution :In CASE of a spinal cord injury, signals for reflex action and involuntary action will GET disrupted.Refle actions are monitored and controlled through the spinal cord of nervous SYSTEM and not by the brain. Infact, nerves from all over the body meet in a bundle in the spinal cord on their WAY to the brain. In case of any injury to the spinal cord, the singnals coming from the nerves as well as signals coming to the receptors will be disrupted.
Discussion
4738.

Question : A mineral is a substance that can be used by an animal in a form that is

Answer»

an ORGANIC MOLECULE
an INORGANIC molecule or ion
bonded to a vitamin
bonded to several water molecules

Answer :B
Discussion
4739.

Question : A method in which roots are induced on the stem while it is still attached to the parent plant is called

Answer»

layering
cutting
grafting
vivipary

Answer :A
Discussion
4740.

Question : (a) Mention the role of the following organs of human male reproductive system : (i) Testis, (ii) Scrotum, (iii) Vas deferens, (iv) Prostate glands. (b) What are the two roles of testosterone?

Answer»

Solution :(a) (i) Testis : To produce male gametes / sperm or male hormone/testosterone.
(ii) SCROTUM : To PROVIDE optimal temperature to testis for the FORMATION of sperm.
(iii) Vas deferens : To deliver the SPERMS to the urinary BLADDER.
(iv) Prostrate glands : To secrete the fluid which provides nutrition and medium for transport of sperms.
(b) (i) Regulates formation of sperms, (ii) brings about the changes in boys during adolescence
Discussion
4741.

Question : (a) Mention the role of the following organs of human male reproductive system: (i) Testis, (ii) Scrotum, (iii) Vas deferens, (iv) Prostate glands. (b) What are the two roles of testosterone?

Answer»

Solution :(a) (i) TESTIS: to produce male gametes.
(ii) Scrotum: to provide optimal temperature to testis for the formation of sperm.
(iii) Vas deferens: to DELIVER the sperms to the urinary bladder.
(iv) Prostrate glands: to secrete the fluid which provides nutrition and medium for transport of sperms.
(b) TESTOSTERONE has FOLLOWING roles:
(i) regulates formation of sperms.
(ii) brings about the changes in boys during adolescence.
Discussion
4742.

Question : (a) Mention the role of following organs of human male reproductive system: (i) Testis (ii) Scrotum (iii) Vas deferens (iv) Prostate glands (b) State the reasons why testes are located outside the abdominal cavity.

Answer»

Solution :(a) (i) Male gametes (SPERMS) and male hormone testosterone are produced by testis.
(ii) Sperm FORMATION requires a lower temperature than the normal body temperature. This temperature is `1-3 ""^@`C lower than the temperature of the body. Testis are LOCATED outside the abdominal cavity, in the scrotum to provide right temperature.
(iii) The sperms formed are delivered through the vas-deferens which UNITES with a tube coming from the urinary bladder.
(IV) The prostate glands secrete the fluids which provides nutrition to the sperms and make their transport easier.
(b) They require a lower temperature than the human body temperature for the formation of sperms.
Discussion
4743.

Question : (a) Mention the role of following organs of human male reproductive system: (i) Testis (ii) Scrotum (iii) Vas deferens (iv) Prostate glands (b) State the reasons why testes are located outside the abdominal cavity.

Answer»

Solution :(a) (i) Male gametes (sperms) and male hormone testosterone are PRODUCED by testis.
(ii) Sperm formation requires a lower temperature than the normal body temperature. This temperature is 1-3 `""^@C` lower than the temperature of the body. Testis are located outside the abdominal cavity, in the SCROTUM to provide right temperature.
(iii) The sperms formed are delivered through the vas-deferens which unites with a tube coming from the urinary bladder
(IV) The prostate GLANDS secrete the fluids which provides nutrition to the sperms and make their transport casier.
(b) They require a lower temperature than the human body temperature for the formation of sperms.
Discussion
4744.

Question : A. Mention any two points of difference between acquired and inherited traits. B. If the tail of a mouse is cut for twenty one generations, will the tail occur in the twenty second generation of that mouse? Give reason to support your answer. C. Define the term-Natural Selection.

Answer»

Solution :
B. The mouse will continue to have INFORMATION for PRESENCE of TAIL in its DNA. So, it will continue to have tail because absence of tail is an acquired trait.
C. Natural selection MEANS that nature selects the best trait in a species, leading to survival of fittest and evolution of species.
Discussion
4745.

Question : A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as …….....a. TTWWb. TTwWc. TtWWd. TtWw

Answer»

TTWW
TTWW
TtWW
TtWw

Discussion
4746.

Question : A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make up of the tall parent can be depicted as

Answer»

TTWW
TTww
TtWW
TtWw

Solution :TtWw
Discussion
4747.

Question : A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

Answer»

TTWW
TTww
Ttww
TtWw

Solution :Here SYMBOL T = TALL
W = voilet
t = SHORT
w = WHITE
Discussion
4748.

Question : In one of his experiments with pea plants Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant, in the first generation, F_(1) only tall plants appeared. (i) What happens to the traits of the dwarf plants in this case? (ii) When the F_(1) generation plants were self-fertilised, he observed that in the plants of second generation, F_(2) both tall plants and dwarf plants were present. Why it happened? Explain briefly.

Answer»

Solution :(a) Mendel crossed TALL pea PLANTS with dwarf pea plants.

Mendel.s Observation
The `F_(1)` generation contained all tall plants. When `F_(1)` generation underwent selfing, the trait that was unexpressed in `F_(1)` (dwarf) was observed in some `F_(2)` progeny. Thus, both traits, tall and dwarf, were expressed in `F_(2)` generation in the ratio 3: 1.
Mendel proposed that something was being PASSED UNCHANGED from generation to generation. He called these things factors (presently called genes). Factors contain and carry hereditary information. He also observed that traits might not show up in an individual but were passed to the next generation.
(b) The two contrasting traits other than height USED by Mendel are :
(i) Pod colour : Green pod colour dominant over yellow colour
(ii) Seed shape : Round seed shape dominant over wrinkled seed shape.
Discussion
4749.

Question : A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggest that the genetic make-up of the tall parent can be depicted as

Answer»

TTWW
Ttww
TtWW
TtWw

SOLUTION :TtWW
Discussion
4750.

Question : A membranous layer between the edible part and seed coat of Pinus seed, is a remnant of

Answer»

INTEGUMENT 
nucellus
wall of megaspore
endosperm 

ANSWER :B
Discussion