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4551.

Question : A women uses a device X made of a common metal for preventing pregnancy. This device works by preventing the implantation of fertilised egg cell (or embryo) in the female organ Y. (a) What are the two names of device X ? (b) Name the organ Y. (c ) Can this method of contraception protect a women from acquiring a STD?

Answer»


SOLUTION :N//A
Discussion
4552.

Question : A women uses pills A a as a method of birth control (or preventing pregnancy). The pills A stop the ovaries from releasing ovum into oviducts. Another women uses pills B as a method of birth control. The pills B kill the sperms and prevent pregnancy. (a) What do the pills A contain ? (b) What is the common name of pills A ? (c ) What do the pills B contain ? (d) What is the common name of lills B ? (e) What is the general name of these methods of birth control?

Answer»


SOLUTION :N//A
Discussion
4553.

Question : A woman whose pituitary was damaged by disease can have a baby if she is given

Answer»

small QUANTITIES of FSH and LH each DAY
small quantities of FSH and LH each day and one large dose of LH on 15th day
20 microgram each of estrogen and pro- gesterone each day for 14 DAYS
small quantity of estrogen every day for 28 days after ovulation

Answer :B
Discussion
4554.

Question : A woman has undergone surgical contraceptive method. Will she show the menstruation or not? Justify your answer.

Answer»

Solution :Yes, she will show menstruation till 45 - 48 years. Because oviducts are SURGICALLY blocked whereas menstruation flow takes place mainly due to breakage of lining of UTERINE WALL. This is under the influence of OVARIAN HORMONES.
Discussion
4555.

Question : A woman has only daughters, analyse the situation genetically and provide a suitable explanation.

Answer»

Solution :The woman produces OVA with .X. chromosome. The man produces sperms with .X. and .Y. chromosome which actually determines the sex of the baby. In this CASE, everytime the MALE X chromosome only FUSES with the female X chromosome thus producing XX combination.
Discussion
4556.

Question : A woman has only daughters. Analyze the situation genetically and provides a suitable explanation.

Answer»

Solution :The union of the MALE gamete with the FEMALE gamete results in a ZYGOTE. Any female gamete will ALWAYS have X chromosome while the male gamete might have X or Y chromosome. As the woman has only daughters, the male has contributed X chromosomes all the times, resulting in female OFFSPRINGS.
Discussion
4557.

Question : a) Why does an aqueous solution of an acid conduct electricity. b) How is plaster of paris prepared ? What reaction takes plaster place when its sets to a hard mass.

Answer»

SOLUTION :a) The presence of hydrogen (`H^(+)`) or hydronium(`H_(3)O^(+)`) ions in the aqueous solution of an acid are responsible for conducting ELECTRICITY
b) Plaster of Paris is prepared by HEATING gypsum to a temperature of `100^(@)C` the following REACTION takes place :
`CaSO_(4). 2H_(2)O to CaSO_(4). (1)/(2)H_(2)O + 1 (1)/(2)H_(2)O`
On mixing with water it converts to a hard MASS to form gypsum again i,e the reverse reaction takes place.
Discussion
4558.

Question : a) Why do stars twinkle b) State two properties of the image formed by the eye lens on the retina.

Answer»

SOLUTION :(a) Stars TWINKLE due to atmospheric refraction of STARLIGHT as the stars are very far away. They behave as almost point sources of light as on account of atmospheric refraction. The path rays of light coming from the STAR goes on varying slightly the apparent position of the star fluctuates and the amount of starlight entering the EYC flickers. So sometimes the star appears brighter and at some other time fainter, thus the stars twinkle.
(b) i) Image on the retina is real and inverted.
ii) Diminished in size.
Discussion
4559.

Question : (a) Why did Mendel choose garden pea for his experiments? Write two reasons. (b) List two contrasting visible characters of garden pea Mendel used for his experiment. (c) Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.

Answer»

Solution :(a) Reasons:
(i) Pea plant is small and easy to grow.
(ii) A large number of TRUE breeding varieties of pea plant are available.
(iii) Short life cycle.
(iv) Both self and cross pollination can be made possible.
(b) Contrasting characters:
Round /WRINKLED seeds
Tall/Short PLANTS
White/purple flowers
Green/yellow seeds
(c) When Mendel crossed two pea plants with a pair of contrasting characters only one character appeared in all the members of `F_(1)`progeny, the others remain hidden.
On selfing `F_(1)`the hidden characters reappeared in just 25% of the offsprings and the other 75% shared the characters expressed in `F_(1)`.
Mendel concluded that the character which expresses itself in `F_(1)`and in 75% of the individuals of `F_(2)` is dominating while the other is recessive.
Discussion
4560.

Question :a) Why are we not able to see the things clearly when we come out of a dark room? b) Why does the sun appear reddish early in the morning.

Answer»

Solution :a) When we are in dark, pupil size is bigger, as we come out of dark room, its size needs to become smaller. For that time interval PERSON is UNABLE to see.
B) During sunrise, the light rays coming from the sun have to travel a greater distance in the earth.s atmosphere before reaching our eyes. In this journey, the SHORTER wave length of lights are scattered out and only longer wavelength are able to reach our eyes. Since BLUE colour had a shorter wavelength and red colour has longer wave length, the red colour is able to reach our eyes after the atmospheric scattering of light. Therefore the sun appear reddish early in the morning.
Discussion
4561.

Question : Write equations for the reactions. (i) Iron with steam (ii) Calcium and potassium with water

Answer»

Solution :In the formation of ionic compounds, positive ions and negative ions precipitate. These are closely packed and the ionic compounds exist as crystalline solids. They have strong INTER - ionic process of ATTRACTION and have high metling and boiling points.
i) `3FE + 4H_(2)O to FC_(2)O_(4)+H_(2)`
II) `Ca+2H_(2)O TOCA(OH)_(2)+ H_(2)`
`2K + 2H_(2)O to 2KOH+H_(2)`
Discussion
4562.

Question : a) Whatis an esterification reaction ? (b) Write a chemical equation in each case to represent the following types of chemical reaction of organic compounds : (i) Oxidation reaction (ii) Addition reaction (iii) Substitution reaction.

Answer»

Solution :When carbonic acid REACTS with alcohol n the presenee of cone. `H_(2)SO_(4),` PLEASANT fruity smelling compound is formed this type of reaction is called esterification reaction.
`underset("Ethanoic acid")(CH_(3)COOH_(1))+ underset("Ethanol")(C_(2)H_(5)OH_(1))underset(H_(2)SO_(4))overset("Alkaline")rarr underset("Ethyl ethanoate")(CH_(3)COOC_(2)H_(5(1)))+ underset("Water")(H_(2)O_(1)`)
(i) Oxidation reaction :
`underset("Ethanol")(CH_(3)CH_(2)OH)+2[O] underset("KMnO"_(4))overset("Alkaline")rarr underset("Ethonoic")(CH_(3)COOH+H_(2))O`
(ii) Addition rection:
`underset ("Ethene")(CH_(2))=CH_(2)+H_(2)underset("573K")overset("Ni")rarr CH_(3)- CH_(3)`
(iii) Substitution reaction :
`underset("Methane")(CH_4)+Cl_(2) overset("Sunlight")rarr underset("Methylchoride")(CH_(3)Cl+HCl)`
Discussion
4563.

Question : (a) What would happen if all the green plants disappear from the earth ? (b) If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring ? Justify your answer.

Answer»


Answer :(a) Green plants are the SOURCE of food for all the organisms. If all the green plants disappear from the earth, then all the organisms (herbivoures, carnivores and omnivores) will die due to starvation (b) When photosynthesis occurs during the day, the carbon dioxide released by plants by respiration is all used up and not released. SIMILARLY, some of the OXYGEN produced during photosynthesis is used up in respiration. Since the plant here is releasing carbon dioxide and taking in oxygen even during the day, it MEANS that no photosynthesis is taking place
Discussion
4564.

Question : (a) What would be the ratio of chromosomes number betweeen an egg and its zygote ? (b) Distinguish between a gamete and a zygote.

Answer»


SOLUTION :N//A
Discussion
4565.

Question : (a) What is variation? How is variation created in a population ? How does the creation of variation in a species promote survival ? (b) Explain how, offspring and parents of organisms reproducing sexually have the same number of chromosomes.

Answer»

Solution :(a) Variation is occurrence of DIFFERENCES between organisms.
Variations are created in a population in different ways:
(i) There may be minor changes/errors during DNA COPYING mechanism which happens before any cell division. These variations may go on accumulating from previous generations, ultimately leading to visible changes.
(ii) in SEXUALLY reproducing organisms, the traits of two individuals combine and give rise to new combination in the progeny. This also leads to variation.
(iii) Thus combining variations from two or more individuals would thus create new combinations of variations.
Organisms with suitable variations will have better chances of survival. Depending on the nature of variation, different individuals would have different kind of advantages.
(b) in sexually reproducing organisms each cell has two copies of each chromosome, one each from the male and female parent. During gamete formation, one chromosome from each pair goes to a gamete. Hence, the gametes have half the number of chromosomes, but one chromosome of each pair. When two gametes combine, they restore the NORMAL number of chromosome in the progeny.
Discussion
4566.

Question : (a) What type of plants reproduce by sexual reproduction method ? (b) What is seed ? What are thepart of seed ? Exaplain with the help of a labelled diagram.

Answer»


SOLUTION :N//A
Discussion
4567.

Question :a) What is Tyndall effect? Give two examples for Tyndall effect. b) What is the meaning of power of accommodation of eye? How does this help us to see objects at different distances?

Answer»

Solution :(a) The scattering of light by the particles in a colloidal medium is called Tyndall effect.
Examples :
SUNLIGHT passing through a DENSE FOREST.
Focusing a beam of red light-in milk.
Passing a blue light to a dark room.
(b) The ability of eye to focus both near and distant objects, by adjusting the focal length is called power of accommodation of the eye. When the ciliary muscles are RELAXED, the eye lens becomes thin, the focal length increases and the distant objects are clearly visible to the eyes. To SEE the near by objects clearly, the ciliary muscles contract making the eye lens thicken. Thus the focal length of the eye lens decrease and the near by objects become visible to the eyes. Hence the human eye lens is able to adjust its focal length to view both distant objects
Discussion
4568.

Question : a) What will be the formula and electron dot structure of cyclopentane. b) How would you distinguish experimentally between an alcohol and carboxylic acid.

Answer»

Solution :Theformula for cyclopentane is `C_5 H_(10)` . Its electron dot structure is given below.

We can distinguish betwecn an alcohol and a carboxylic acid on the BASIS of their REACTION with carbonate and hydrogen carbonates. Acids reacts with carbonate and hydrogen carbonate to evolve `CO_2` gas that TURMS lime water milky.
Metal carbonate / metal hydrogen carbonate + carboxylic acid.
`"" darr`
Salt + water + carbondioxide .
Alcohols on the other HAND, do not react with carbonates and hydrogencarbonates.
Discussion
4569.

Question : (a) What substances are contained (i) in oral pills, and (ii) in vaginal pills, used as contraceptives ? How do they work ? (b) How does copper-T prevent pregnancy ? (c) Name the disease caused by HIV.

Answer»


SOLUTION :N//A
Discussion
4570.

Question : (a) What is the name of surgical method of birth control in human males in which the sperm ducts are cut and ligated (tied) at both ends ? (b) What is the name of surgical method of birth control in human females in which the oviducts are cut and ligated (tied) at both ends ? (c) Name the contraceptive device used by the human males which acts as a sheath over the male organ and traps the sperms in it. (d) Name the contraceptive device used by human females which is put over the cervix.

Answer»


SOLUTION :N//A
Discussion
4571.

Question : (a) What is tissue culture ? (b) Name any four types of ornamentalplants which are being produced by tissue culture techique. (c) What is the important of DNA coyping in reproduction ? Explain with axample. (d) How does reproduction help in providing statbility to populations of species ? (e) Why is variation during reproduction beneficial to the species but not necessarily for the individual ?

Answer»


SOLUTION :N//A
Discussion
4572.

Question : a) What is thermite reaction ? b) Q is an element which is one in copper, zinc, aluminium and iron, its properties are as follows. i) Q_(2)O_(3) is found in nature but not affected by water. ii) Two chlorides with formula QCI_(2) and QCI_(3) are formed by the metal. Identify the metal

Answer»

Solution : a) The displacement reaction which is highly exothermic and the METAL produced is in molten STATE is CALLED thermite reaction.
i). SINCE the oxide of the metal is `Q_(2)Q_(3)` its valence is 3. therefore out of the mentioned metal only adumimium and iron can be the metal with properties mentioned above.
ii) `QCI_(2)` and `QCI_(3)` MUST be iron as it shows varible valency of two and three. `FeCl_(2)` and `FeCl_(3)` are the chlorides.
Discussion
4573.

Question : a) What is the resistance of a conductor? Mention the factors on which the resistance of a conductor depend. b) b) An electric bulb of 200 Omegadraws a current of 1 ampere. Calculate the power of the bulb the potential differenceat its ends and the energy in KWh consumed burning it for 5h.

Answer»

Solution :a) Resistance of a conductor is the PROPERTY of a conductor by VIRTUE of which it opposes the flow of current through it. The resistance of the conductor depends i) on its length ii) on its area of cross section and ii) on the nature of its materials.
b) Power of the bulb
Power of the bulb, `P = I^2 R = (1)^2 xx 200`
`P = 200 W`
Energy consumed by bulb in 5h in burning.
= Power x TIME
= 200 x 5
= 1000 wh = 1 kwh.
Discussion
4574.

Question : (a) What is the name of surgical method of birth control (or preventing pregnancy) which is carried out (i) in men and (ii) in women ? (b) Name the part of a seed which (i) contains stored food (ii) grows into root , and (iii) grows into shoot.

Answer»


SOLUTION :N//A
Discussion
4575.

Question : (a) What is the life support system of a fetus ? (b) How long does a human body take to develop before birth? (c) What is the name of narrow opening between the uterus and the vagina.

Answer»


SOLUTION :N//A
Discussion
4576.

Question : (a) What is the cutting respect of plants for propagation purposes ? (b) What care should be taken while making a cutting from a plant? (c) Describe the cutting method for the artificial propagation of plants. Illustrate your answer with the help of labelled diagrams. (d) Name any two plants which are usually propagated by the cutting method.

Answer»


SOLUTION :N//A
Discussion
4577.

Question : (a) What is the difference between the two asexual methods of reproduction : fission and fragmentation. ? ltbr (b) Name one organism which reproduce by fission another which reproduces by fragmentatio. (c) What is meant by multiple fission ? Name onr organism which reproduces by the process of multiple fission. (d) Describe the processs of reproduction in Hydaa with the help of labelled diagrams. What is the name of this process of reproducton. ? (e) Name one unicellular organism which reproduces by the same asexual process as Hydra.

Answer»


SOLUTION :N//A
Discussion
4578.

Question : (a) What is the basic difference between asexual reproduction and sexaul reproduction ? (b) Which of the following organisms reproduce by sexual method and which by asexual method ?Amoeba, Cats, Humans, Hydra, Birds

Answer»


SOLUTION :N//A
Discussion
4579.

Question : (a) What is puberty? Who attains pyberty at an earlier age in human beings: male or female (boy or girl) ? (b) Mention two functions each of (i) human testes , and (ii) human ovaries.

Answer»


SOLUTION :N//A
Discussion
4580.

Question : a] What is puberty ? b] Describe in brief the functions of the following parts in thehuman male reproductive system: {i) Testes (ii) Seminal vesicle (iii) Vas deferens {iv) Urethra OR Explain the significant function of each structure in human male reproductive system. c] Why are testes located outside the abdominal cavity? d] State how sperms move towards the female germ cell?

Answer»

Solution :a] The period of life when production of GERM cells, i.e. ova (female) and SPERM (male) start in the body. This period of sexual maturation is called puberty.
b] i] Testes: Paired, oval-shaped male sex glands. CONSIST of seminiferous tubules, where the sperms are produced. Produce a male sex hormone called testosterone.
II] Seminal VESICLES: Fluid and nutrients combine with sperm to form semen, Milky, viscous fluid contains fructose, proteins and other chemicals for nourishing and stimulating sperms. (iii) Vas deferens : • Also known as sperm duct. • Connects testes for the passage of semen (iv) Urethra : Common passage for both the sperms and urine, but never carries both of them at the same time.
c] Testes are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than the normal body temperature
d] The sperms are tiny bodies that consist of mainly genetic material and a long tail that helps them to move towards the female germ-cell
Discussion
4581.

Question : (a) What is pollination ? State its significance (b) How does fertilisation occurs in flowers ? Name the parts of the flower that develop into (i) seed and (ii) fruit after fertilisation.

Answer»

SOLUTION :(a) The transfer of pollen from anther to STIGMA of suitable flower is pollination This results in fertilisation and hence formation of next generation
(b) After pollination, the pollen germinates to form pollen tube that CARRIES male germ cells. It grows to reach embryo sac, where these germ cells are released and fertilisation takes PLACE.
(i) Embryo sac forms seed.
(ii) Ovary forms the fruit.
Discussion
4582.

Question : (a) What is pollination ? Give its two types. (b) Draw a longitudinal section of female reproductive part of a flower showing germination of pollen grain. Label on it the following: (i) Stigma. (ii) Pollen tube with a male germ cell. (iii) Female germ cell.

Answer»

SOLUTION :POLLINATION is the process of TRANSFER of pollen grains from anther of a flower to the stigma of a same flower or another flower of same species. DEPENDING on the flower, it is of two types:(i) Self pollination - When pollen from the anther of the same flower lands on its stigma
(II) Cross pollination - When pollen from one flower lands on stigma of another flower of same species, with the help of air, water, insects, birds or bats.
(b)
Discussion
4583.

Question : (a) What is ovulation ? How often does it happen in human females ? (b) Where does fertilisation take place in human females ? (c) Explain why, fertilisation is possible if mating takes place during the middle of menstrual cycle . (d) What is meant by implantation? (e) What is placenta ? What is its function ? (f) What joins embryo to placenta in mother's body ?

Answer»


SOLUTION :N//A
Discussion
4584.

Question : (a) What is myopia ? State the two causes of myopia (b) Why is the normal eye unable to focuson an object placed wtithin 10 em from the eye?

Answer»

Solution :Myopic cye can see objects al shorl DISTANCE inability of the eye in viewing long distant objects the image.falls before retina causcs of myopia.
(i) Elongation of eye ball
(ii) Excessive curvature in
(b) A normal eye is unable to clearly see the objects placed CLOSER then 25 cm because the ciliary MUSCLES of eyes are unable to contract beyond a certain LIMIT
When the objcct is placed at a distance less or more than 25 cm from the eye than the object appears blurred and induces STRAIN in the eyes.
Discussion
4585.

Question : (a) What is meant by vegetative propagation? (b) Vegetative propagation involves the growth and development of something present in the old part of the plant to from a new plant. What is this something ? (c) Why do green grass plants spring up in dry fields on their own after rains ?

Answer»


SOLUTION :N//A
Discussion
4586.

Question : (a) What is meant by 'unisexual flowers' and 'bisexual flowers' ? Give two examples of each. (b) What is pollination ? How does pollination occur ? (c) Describe the process of fertilisation in a flower with the help of labelled diagrams. (d) What changes take place in the flower after fertilisation which lead to the formation of seeds and fruit ?

Answer»


SOLUTION :N//A
Discussion
4587.

Question : (a) What is meant by the term, artificialpropagation of plants (b) Name three common method which are used for the artifical propagation of plants. (c) Name two plants which are usually propgated b y artificial propagation method. Name the method of articial propagation used in each case.

Answer»


SOLUTION :N//A
Discussion
4588.

Question : Name the two laws of inheritance postulated by Mendel?

Answer»

Solution :a) Speciation is the evolution of reproduction isolation among once interbreeding POPULATION factors which can lead to speciation are:
* Genetic drift : over generations, genetic drift may accumulate which lead to speciation
*Natural selection : Natural selection which may give rise to speciation.
*Severe DNA change
*A variation may occur which does not allow sexual ACT between two groups.
*B) i) The law of regeneration
ii) The law of independence assortment.
Discussion
4589.

Question : (a) What is meant by graffing as means of propagation of propagation in plants ? (b) Define 'stock' and ' scion' . (c) Descirbe the grafting method fro the artificial propagation of plants with the help of labelled diagrams. (d) Name two fruit tress which are usually propagation by grafting method. (e) State two advantage of grafting method of artificial propagation of plants (f) What is differene between the cutting method and grafting method for the artificial propagation of plants ?

Answer»


SOLUTION :N//A
Discussion
4590.

Question : (a) What is meant by regeneration ? Name two animals which cn regenerate fully from their cut body parts. (b) Explain, why, more complex multicellular organisms cannot give rise to new organisms through regeneration

Answer»


SOLUTION :N//A
Discussion
4591.

Question :a) What is meant by least distance of distinct vision? b) What happens to the image distance in the eye when we increases the distance of an object from the eye.

Answer»

Solution :a) It is the minimum distance up to which eye can see clearly and is called the least distance of distinct vision.
b) The size of the eye can change, so the image distance is fixed when we increase the distance if the eye does not change, due to power of accommodation of the eye, FOCAL length of the eye LENS is changed, which compensates the increase in OBJECT distance. Hence image distance remains fixed and image is FORMED on the retina of the eye.
Discussion
4592.

Question : Draw the structure of the following compounds and identify the functional group present in them. (i) Butanoic acid (ii)Bromopropane (iii)Butyne

Answer»

Solution :It is the reaction that formS soap when an ester reacts with water in the presence of base a salt of carboxylic acid and an alcohol are produced. SUCHA reaction is called saponification.
For example: When ethyl ethanote is heated with a solution of sodium hydroxide sodium cthanote and ethanol are produced.
`CH_(3)COOC_(2)H_(5)+NaOHrarrCH_(3)COONa+C_(2)H_(5)OH`
FUNCTION group is carboxylie acid

(ii) Function group is Bromine
`H - underset("H")underset(|)overset("H")overset(|)(C)-underset("H")underset(|)overset("Br")overset(|)(C)- underset("H")underset(|)overset("H")overset(|)(C)- underset("H")underset(|)overset("H")overset(|)(C)-H`
Discussion
4593.

Question : (a) What is meant by contraceptive ? What are the different methods of contraceptive ? (b) What is done in the contraceptive method known as (i) vasectomy, and (ii) tubectomy?

Answer»


SOLUTION :N//A
Discussion
4594.

Question : (a) What is mean by the term fission as used in biology? (b) How does binary fission differ from multiple fission (c) Name oce organism which reproduces by binary fisison and another which reproduces by multiple fission. (d) State wheter the above named organisms ae animals or plants.

Answer»


SOLUTION :N//A
Discussion
4595.

Question : a) What is hypermetropia? What are the two causes of theis defect of vision. b) What is the colour of the clear sky during day time. Give reason for it.

Answer»

Solution :a) Hypermetropia is the DEFECT in which a person can see distance objects CLEARLY but cannot see the nearby objects.
The two possible CAUSES of this defect are :
* Increase in the focal length of the eye lens,
* Eyeball gets shortened.
b) When sunlight passes through the atmosphere having the molecules of air and other fine particles whose size is smaller than the wave length of visible LIGHT these molecules and particles scatter the blue colour more strongly than the other colours of spectrum as the wave length of blue colour is more. This SCATTERED blue light enters our eye, so the colour of sky apepars blue to us during day time.
Discussion
4596.

Question : a) What is hydrogenation? What is its industrial application. b) Give the names of the following i) An aldehyde derived from ethane. ii) Ketone derived from butane iii) Compound obtained by the oxidation of ethanol by chromic anhydride.

Answer»

Solution :Addition of HYDROGEN to unsaturated hydrocarbons in presence of a catalyst such as nickel or palladium to form saturated hydrocarbons is CALLED hydrogenation For Example:-

Industrial application:-
The process of hydrogenation is used in industry to convert vegetable oils to vanaspathi ghee

The vegetable oil CONTAINS a number of unsaturated CARBON chain having double bonds between carbon atoms when `H_(2)` is bubbled through vegetable oils in presence of nickel as catalyst at 437K some of the double bonds add `H_(2)` to form saturated carbon chain. As a result of this partial hydrogenation, oils are converted into solid fats.
b)i)Ethanal(`CH_(3)CHO`)
ii) Butanone (`CH_(3)CO CH_(2)CH_(3)`)
iii) Ethanol (`CH_(3)CHO`).
Discussion
4597.

Question : a) What is a universal indicator ? b) A milk man adds a very small amount of baking soda to fresh milk. i) Why does he shift the pH of the fresh milk from 6 to slightly alkaline. ii) Why does this milk take a long time to set as curd.

Answer»

Solution :a) A UNIVERSAL indicator is a mixture of a number of indicators which shows different colours at different pH values,
b) Since the fresh milk is acidic it turns SOUR early in presence of baking SODA, milk become alkaline and does not TURN sour easily because of alkali does not ALLOW the milk to become more acidic early
ii) When the milk sets to curd the pH decreases i.e., it becomes more acidic the presence of alkali does not allow it to become more acidic easily hence it will take a long time to set as curd.
Discussion
4598.

Question : (a) Whatis being shown in the given Fig. A and B ?(b)Name the instrument used to measure this value.(c)Why is their difference in the reading in Fig. A and B ?(d)Discuss some common reasonsthat may lead to increase in thisvalue.

Answer»

Solution :(a) The given figure shows MEASUREMENTOF blood pressure.
(b)Blood pressure is measured by the instrument of blood pressure.
(c)Fig. A shows systolic pressure while Fig. B showsdiastolic pressure.
The force that blood EXERTS against the WALL of a vessel is called blood pressure. This pressure is much greater in arteires than in veins. The pressure of blood inside the arteryduringventricularsystole (contraction) is called systolic pressureand pressure in arteryduringventricular diastole (relaxation) is called diastolic pressure. The normal systolic pressure is about120 mm and distolic is 80 mm of Hg.
Since, during contraction the BPincreasesand duringrelaxation the BPdecrease, hencethe difference.
(d)Common reasons for increase in BP that leadsto Hypertension are :
(i) GENETIC factors
(ii)Sedentary life style
(iii)Obesity
(iv)Poor eating habits
(v)Stress.
Discussion
4599.

Question : (a) What is gestation period ? How much is the gestation period in humans ? (b) Name one method of contraception which also protects against sexually transmitted diseases. (c) Name one sexually transmitted disease for which no definite cure has been found so far. What is the causative organsim of this disease?

Answer»


SOLUTION :N//A
Discussion
4600.

Question : (a) What is a tuber? Name one stema tuber and one root tuber. (b) What is name of organ of propagation present in a tuber ? (c) Name one commonly used vegetable which is propagated by using tubers.

Answer»


SOLUTION :N//A
Discussion