Function/Importance of ciliary muscles: The ciliary muscles modify the curvature of the eye lens to enable the eye to focus objects at varying distances/help in adjusting the focal length of the eye lens.
Function/Importance of ciliary muscles: The ciliary muscles modify the curvature of the eye lens to enable the eye to focus objects at varying distances/help in adjusting the focal length of the eye lens.
(a) While doing experiments with pea plants when Mendel crossed pollinated pure tall pea plants with pure dwarf pea plants, only tall plants were obtained in F1 generation. On self-pollinating the F1 progeny, both tall and dwarf plants appeared in F2 generation in the ratio 3 : 1. Appearance of tallRead more
(a) While doing experiments with pea plants when Mendel crossed pollinated pure tall pea
plants with pure dwarf pea plants, only tall plants were obtained in F1 generation. On self-pollinating the F1 progeny, both tall and dwarf plants appeared in F2 generation in the
ratio 3 : 1.
Appearance of tall character in both the F1 and F2 shows that tallness is the dominant character. The absence of dwarf character in F, generation and its reappearance in F2 generation shows dwarfness is the recessive character.
(b) When Mendel conducted a dihybrid cross with pea plants having two sets of characters, he obtained only one set of parental characters in F1 generation, whereas in F2 generation he obtained both the set of parental characters now recombined in the ratio of
9 :3 :3:1.
The appearance of new recombinants in the F2 generation along with parental type shows that traits are inherited independently.
(a) Testis - Secretes male hormone testesterone. Functions of the hormone: (1) Formation of sperms. (ii) Development of secondary sexual characters. (b) (l) Fallopian tube/oviduct (ii) Uterus Nourishment of the embryo inside the mother's body: Placenta is a special disc-like tissue embedded in the mRead more
(a) Testis – Secretes male hormone testesterone.
Functions of the hormone:
(1) Formation of sperms.
(ii) Development of secondary sexual characters.
(b) (l) Fallopian tube/oviduct
(ii) Uterus
Nourishment of the embryo inside the mother’s body:
Placenta is a special disc-like tissue embedded in the mother’s uterine wall and connected to the foetus/embryo.
Placenta provides a large surface area for glucose and oxygen/nutrients to pass from the mother’s blood to the developing embryo/foetus.
Biodegradable substances: These are the substance which can be broken down into simpler substances by nature / decomposers/bacteria/saprophytes/saprobionts. Example: Human excreta, vegetable peels, etc. Non-biodegradable substances: These are the substance which cannot be broken down into simpler suRead more
Biodegradable substances: These are the substance which can be broken down into simpler substances by nature / decomposers/bacteria/saprophytes/saprobionts.
Example: Human excreta, vegetable peels, etc.
Non-biodegradable substances: These are the substance which cannot be broken down into simpler substances by nature/decomposers.
Example: Plastic, glass (or any other).
Habits to be adopted:
– Use of separate dustbins for biodegradable and non-biodegradable waste.
– Reuse of things, such as poly bags, glass bottles, etc. again and again.
– Avoid use of plastic/polythene for packing.
– Use of cotton/jute bags for carrying vegetables, etc.
(a) Speciation: It is evolution of a new species from pre-existing species. (l) Occurring due to accumulation of variations. (ii) By processes like genetic drift/geographical barriers like mountains, rivers etc,. leading to incapability to reproduce amongst themseir.es in the population. (b) NaturalRead more
(a) Speciation: It is evolution of a new species from pre-existing species.
(l) Occurring due to accumulation of variations.
(ii) By processes like genetic drift/geographical barriers like mountains, rivers etc,. leading to incapability to reproduce amongst themseir.es in the population.
(b) Natural selection:
(l) Change in frequency of some genes in a population.
(ii) Which give survival advantage to a species from elimination.
(lii) Example – In a population of beetles, a new variation (green colour) get survival benefit/ advantage to red beetles whereas other red perishes.
Homologous organs - The study of homologous organs suggests that the organs having same structure, but performing different functions, have evolved from a common ancestor. Example: Forelimbs of a frog, lizard, bird and man are homologous organs. Analogous organs - They show adoption of organs for coRead more
Homologous organs – The study of homologous organs suggests that the organs having same structure, but performing different functions, have evolved from a common ancestor.
Example: Forelimbs of a frog, lizard, bird and man are homologous organs.
Analogous organs – They show adoption of organs for common use.
Example: Wings of butterfly and wings of bat are analogous organs.
Fossils – They provide the missing links between two species.
Example: Archeopteryx/fossils of some dinosaurs with feathers. Archeopteryx provides a connecting link between reptiles and birds (Avian).
Significance of reproductive health in the society: (i) Prevention of STDs, (ii) Advantage of small family, (lii) Less mortality among newborns, (iv) Reduces the cases of maternal mortality. Related areas which have improved over the last 50 years: - Family Planning - Decrease in STD cases
Significance of reproductive health in the society:
(i) Prevention of STDs,
(ii) Advantage of small family,
(lii) Less mortality among newborns,
(iv) Reduces the cases of maternal mortality.
Related areas which have improved over the last 50 years:
– Family Planning
– Decrease in STD cases
Chromosomes: These are thread-like structures made up of DNA found in the nucleus. The original number of chromosomes becomes half during gamete formation. Hence, when the gametes combine, the original number of chromosomes gets restored in the progeny.
Chromosomes: These are thread-like structures made up of DNA found in the nucleus. The original number of chromosomes becomes half during gamete formation. Hence, when the gametes combine, the original number of chromosomes gets restored in the progeny.
Specific characteristics of sexual reproduction: (l) Two partners are involved. (ii) Two dissimilar gametes are formed, gamete formation involves meiosis. (lii) Variations are produced. (iv) It occurs in all the higher and some of the lower organisms. (v) Fertilization/fusion of gametes leads to zygRead more
Specific characteristics of sexual reproduction:
(l) Two partners are involved.
(ii) Two dissimilar gametes are formed, gamete formation involves meiosis.
(lii) Variations are produced.
(iv) It occurs in all the higher and some of the lower organisms.
(v) Fertilization/fusion of gametes leads to zygote formation.
(vi) It is comparatively a slow process.
(vii) Each partner produces gamete – sperms (male) .
(viii) Ova or egg (Female).
Electronic configuration of element with atomic number 16 is 2, 8, 6. Since it has 3 shells, the period number will be 3. Since the number of valence electrons is 6, the group number will be 10 + 6 = 16. Valency of the element will be 8 - valence electrons, i.e. 8 - 6 = 2.
Electronic configuration of element with atomic number 16 is 2, 8, 6.
Since it has 3 shells, the period number will be 3.
Since the number of valence electrons is 6, the group number will be 10 + 6 = 16.
Valency of the element will be 8 – valence electrons, i.e. 8 – 6 = 2.
Write the importance of ciliary muscles in the human eye. Name the defect of vision that arises due to gradual weakening of the ciliary muscles in old age. What type of lenses are required by the persons suffering from this defect to see the objects clearly?
Function/Importance of ciliary muscles: The ciliary muscles modify the curvature of the eye lens to enable the eye to focus objects at varying distances/help in adjusting the focal length of the eye lens.
Function/Importance of ciliary muscles: The ciliary muscles modify the curvature of the eye lens to enable the eye to focus objects at varying distances/help in adjusting the focal length of the eye lens.
See lessHow do Mendel’s experiments show that the (a) traits may be dominant or recessive, (b) traits are inherited independently?
(a) While doing experiments with pea plants when Mendel crossed pollinated pure tall pea plants with pure dwarf pea plants, only tall plants were obtained in F1 generation. On self-pollinating the F1 progeny, both tall and dwarf plants appeared in F2 generation in the ratio 3 : 1. Appearance of tallRead more
(a) While doing experiments with pea plants when Mendel crossed pollinated pure tall pea
See lessplants with pure dwarf pea plants, only tall plants were obtained in F1 generation. On self-pollinating the F1 progeny, both tall and dwarf plants appeared in F2 generation in the
ratio 3 : 1.
Appearance of tall character in both the F1 and F2 shows that tallness is the dominant character. The absence of dwarf character in F, generation and its reappearance in F2 generation shows dwarfness is the recessive character.
(b) When Mendel conducted a dihybrid cross with pea plants having two sets of characters, he obtained only one set of parental characters in F1 generation, whereas in F2 generation he obtained both the set of parental characters now recombined in the ratio of
9 :3 :3:1.
The appearance of new recombinants in the F2 generation along with parental type shows that traits are inherited independently.
(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) fertilizations takes place, (iii) implantation of the fertilized egg occurs. Explain how the embryo gets nourishment inside the mother’s body.
(a) Testis - Secretes male hormone testesterone. Functions of the hormone: (1) Formation of sperms. (ii) Development of secondary sexual characters. (b) (l) Fallopian tube/oviduct (ii) Uterus Nourishment of the embryo inside the mother's body: Placenta is a special disc-like tissue embedded in the mRead more
(a) Testis – Secretes male hormone testesterone.
See lessFunctions of the hormone:
(1) Formation of sperms.
(ii) Development of secondary sexual characters.
(b) (l) Fallopian tube/oviduct
(ii) Uterus
Nourishment of the embryo inside the mother’s body:
Placenta is a special disc-like tissue embedded in the mother’s uterine wall and connected to the foetus/embryo.
Placenta provides a large surface area for glucose and oxygen/nutrients to pass from the mother’s blood to the developing embryo/foetus.
Differentiate between biodegradable and non-biodegradable substances with the help of one example each. List two changes in habit that people must adopt to dispose non-biodegradable waste, for saving the environment.
Biodegradable substances: These are the substance which can be broken down into simpler substances by nature / decomposers/bacteria/saprophytes/saprobionts. Example: Human excreta, vegetable peels, etc. Non-biodegradable substances: These are the substance which cannot be broken down into simpler suRead more
Biodegradable substances: These are the substance which can be broken down into simpler substances by nature / decomposers/bacteria/saprophytes/saprobionts.
See lessExample: Human excreta, vegetable peels, etc.
Non-biodegradable substances: These are the substance which cannot be broken down into simpler substances by nature/decomposers.
Example: Plastic, glass (or any other).
Habits to be adopted:
– Use of separate dustbins for biodegradable and non-biodegradable waste.
– Reuse of things, such as poly bags, glass bottles, etc. again and again.
– Avoid use of plastic/polythene for packing.
– Use of cotton/jute bags for carrying vegetables, etc.
Explain the following: (a) Speciation (b) Natural Selection
(a) Speciation: It is evolution of a new species from pre-existing species. (l) Occurring due to accumulation of variations. (ii) By processes like genetic drift/geographical barriers like mountains, rivers etc,. leading to incapability to reproduce amongst themseir.es in the population. (b) NaturalRead more
(a) Speciation: It is evolution of a new species from pre-existing species.
See less(l) Occurring due to accumulation of variations.
(ii) By processes like genetic drift/geographical barriers like mountains, rivers etc,. leading to incapability to reproduce amongst themseir.es in the population.
(b) Natural selection:
(l) Change in frequency of some genes in a population.
(ii) Which give survival advantage to a species from elimination.
(lii) Example – In a population of beetles, a new variation (green colour) get survival benefit/ advantage to red beetles whereas other red perishes.
Explain with an example for each, how the following provides evidences in favour of evolution in organisms: (a) Homologous organs (b) analogous organs (c) Fossils.
Homologous organs - The study of homologous organs suggests that the organs having same structure, but performing different functions, have evolved from a common ancestor. Example: Forelimbs of a frog, lizard, bird and man are homologous organs. Analogous organs - They show adoption of organs for coRead more
Homologous organs – The study of homologous organs suggests that the organs having same structure, but performing different functions, have evolved from a common ancestor.
See lessExample: Forelimbs of a frog, lizard, bird and man are homologous organs.
Analogous organs – They show adoption of organs for common use.
Example: Wings of butterfly and wings of bat are analogous organs.
Fossils – They provide the missing links between two species.
Example: Archeopteryx/fossils of some dinosaurs with feathers. Archeopteryx provides a connecting link between reptiles and birds (Avian).
List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over the past 50 years in our country.
Significance of reproductive health in the society: (i) Prevention of STDs, (ii) Advantage of small family, (lii) Less mortality among newborns, (iv) Reduces the cases of maternal mortality. Related areas which have improved over the last 50 years: - Family Planning - Decrease in STD cases
Significance of reproductive health in the society:
See less(i) Prevention of STDs,
(ii) Advantage of small family,
(lii) Less mortality among newborns,
(iv) Reduces the cases of maternal mortality.
Related areas which have improved over the last 50 years:
– Family Planning
– Decrease in STD cases
What are chromosomes? Explain how in sexually reproducing organisms the number of chromosomes in the progeny is maintained.
Chromosomes: These are thread-like structures made up of DNA found in the nucleus. The original number of chromosomes becomes half during gamete formation. Hence, when the gametes combine, the original number of chromosomes gets restored in the progeny.
Chromosomes: These are thread-like structures made up of DNA found in the nucleus. The original number of chromosomes becomes half during gamete formation. Hence, when the gametes combine, the original number of chromosomes gets restored in the progeny.
See lessList six specific characteristics of sexual reproduction.
Specific characteristics of sexual reproduction: (l) Two partners are involved. (ii) Two dissimilar gametes are formed, gamete formation involves meiosis. (lii) Variations are produced. (iv) It occurs in all the higher and some of the lower organisms. (v) Fertilization/fusion of gametes leads to zygRead more
Specific characteristics of sexual reproduction:
See less(l) Two partners are involved.
(ii) Two dissimilar gametes are formed, gamete formation involves meiosis.
(lii) Variations are produced.
(iv) It occurs in all the higher and some of the lower organisms.
(v) Fertilization/fusion of gametes leads to zygote formation.
(vi) It is comparatively a slow process.
(vii) Each partner produces gamete – sperms (male) .
(viii) Ova or egg (Female).
Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic numb
Electronic configuration of element with atomic number 16 is 2, 8, 6. Since it has 3 shells, the period number will be 3. Since the number of valence electrons is 6, the group number will be 10 + 6 = 16. Valency of the element will be 8 - valence electrons, i.e. 8 - 6 = 2.
Electronic configuration of element with atomic number 16 is 2, 8, 6.
See lessSince it has 3 shells, the period number will be 3.
Since the number of valence electrons is 6, the group number will be 10 + 6 = 16.
Valency of the element will be 8 – valence electrons, i.e. 8 – 6 = 2.