Q. What is meristematic tissue? Explain. Ans- Meristematic tissues are found at all growing points, such as the tip of roots, stems and branches where growth in length occurs. These meristems are called apical meristems. These tissues occur right from the birth of the plant and are, therefore called primary meristems. Characteristics of meristema . . .
Natural disasters- Earthquake An earthquake is sudden shaking of ground caused by movements of vibration deep inside the earth. These vibration release great energy and cause that part of earth to quiver. Earthquake of high intensity often cause great destruction on the earth’s surface. A natural phenomenon that cannot be predicted is an& . . .
Natural disaster-tidal waves or tsunami A tsunami is a series of fast moving waves in the ocean caused by powerful earthquakes or volcanic eruptions. A tsunami has a very long wavelength. It can be hundreds of kilometers long. Usually, a tsunami starts suddenly. The waves travel at a great&n . . .
NATURAL DISASTER-DROUGHT Drought is a continuous period of dry weather, when an area gets less than its normal amount of rain, over months or even years. Crops and other plants need water to grow, and land animals need it to live. It can become dangerous to people and other animals; causing& . . .
Q. Describe various methods of agricultural practices involved in crop production and management. Ans: Preparation of soil by tilling and levelling. Sowing of seeds into prepared soil. Adding manure and fertilisers for replenishment and enrichment of soil and healthy growth of crops. The supply of water to crops at appropriate interv . . .
Q. Write a paragraph in your own words on each of the following. (a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing Ans (a) Preparation of soil- The preparation of soil is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep into . . .
Q. What is irrigation? Describe two methods of irrigation which conserve water. Ans: The supply of water to crops at different intervals is called irrigation. The two methods of irrigation which conserve water are as follows: (i) Sprinkler System: Under this method, the perpendicular pipes, having rotating nozzles on top, are joined to the . . .
Eutrophication Nutrient enrichment of waterbodies due to agricultural run-off which leads to shallowing of waterbodies is known as eutrophication. It is an excessive growth or blooms of algae in lakes rich in nutrients. Normally it takes thousands of years to progress, but human activities have enhanced this process greatly. Human add excessive amou . . .
Q. Write 10 lines on the usefulness of microorganisms in our lives. Ans-Microorganisms are too small to be seen through naked eyes. However, they are vital to plants and the environment. Importance of microorganisms: They are used in winemaking, baking, pickling and other food making processes. Alcoholic fermentation by yeast is widely use . . .
Q. Write a short paragraph on the harms caused by microorganisms. Ans- Microorganisms are harmful in many ways. Some of the microorganisms cause diseases in human beings, plants and animals. Such disease-causing microorganisms are called pathogens. Some microorganisms spoil food, clothing and leather. Some of the common diseases affecting humans are . . .
Q. Write short notes on the following: (a) Cytoplasm (b) Nucleus of a cell Ans (a) Cytoplasm The jelly-like substance between the nucleus and the cell membrane is called cytoplasm. Various cell organelles like ribosomes, mitochondria etc. are suspended inside cytoplasm. It helps exchange and storage of substances among cell organelles. Most . . .
Q. State the difference between eukaryotes and prokaryotes. Ans: Prokaryotes: The cells having nuclear material without nuclear membrane are termed as prokaryotic cells. The organisms with these kinds of cells are called prokaryotes. Examples: Bacteria and blue green algae. Eukaryotes: The cells having a well-organized nucleus with a nuclear membr . . .
Q. What is metamorphosis? Give examples. Ans: The transformation of the larva into an adult through drastic changes is called metamorphosis. Metamorphosis is a biological process which involves sudden and abrupt changes in the body structure of the animal by cell growth and differentiation. It is generally observed in amphibians and insects. Examples . . .
Q. What is menstruation? Explain. Ans: In a female reproductive ovary, the ova begin to mature with the onset of puberty. One ovum matures and released by one of the ovaries once in about 28 to 30 days. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilized and begins to develop. If fertilization d . . .
Q. What are sex hormones? Why are they named so? State their function. Ans: Hormones which constitute the secondary sexual characters are called sex hormones. In general, hormones work instantly when they released in blood stream. Sex hormones are different because they start to work later on. They gradually prepare in the body for reproduction. T . . .