Write two examples each of sexually transmitted diseases caused by (i) virus, (ii) bacteria. Explain how the transmission of such diseases be prevented?
Tabulate two distinguishing features between acquired traits and inherited traits with one example of each.
The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it. Justify this statement with the help of flow chart showing determination of sex of a newborn.
Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.
An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm.
State the difference in colors of the sun observed during sunrise/sunset and noon. Give explanation for each.
(a) What is an ecosystem? List its two main components.
(b) We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain.
All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem. For example a garden is an ecosystem which consists of plants, insects, water, soil etc.
(a) The two components of the ecosystem are − Biotic and Abiotic.
Biotic components comprises of all the living organisms like humans, animals, plants etc and Abiotic component comprises of the nonliving things like air, mineral soil, water and sunlight.
(b) Ponds and lakes are an example of natural ecosystem whereas the aquarium is an example of artificial ecosystem. Ponds do not need to be cleaned because it has microorganisms, like bacteria and fungi that break-down the dead remains and waste products of organisms and clean the pond naturally. The aquarium does not contain soil or decomposing bacteria or fungi which helps in degrading complex organic substance into simple inorganic substance, so it needs to be cleaned from time to time.(a) Define the term 'isomers'.
(b) Draw two possible isomers of the compound with molecular formula C3H6O and write their names.
(c) Give the electron dot structures of the above two compounds.
(a) List three distinguishing features between sexual and asexual types of reproduction.
(b) Explain why variations are observed in the offspring of sexually reproducing organisms?
(a) Identify A, B and C in the given diagram and write their functions.
(b) Mention the role of gamete and zygote in sexually reproducing organisms.