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.
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.