Science: Introduction and MCQs

Ans. a) Mitochondria

Mitochondria

Explanation: Mitochondria is known as the powerhouse of the cell. They are oval-shaped organelles present in most eukaryotic cells. As the site of cellular respiration, Mitochondria transforms molecules of glucose into energy molecules also known as ATP. By breaking the high energy chemical bonds, ATP fuels the cellular process. In other words, Mitochondria oxidises fats and carbohydrates present in the cell to produce carbon dioxide, water and large amount of energy. The released energy is stored in the form of ATP molecules and energy is synthesised.

Ans. d) All above

Golgi Apparatus

Explanation: Golgi Apparatus is made up of a series of flattened, stacked pouches called cisternae. Golgi Apparatus is responsible for transportation, storage modification and packaging proteins and liquids, to be delivered at a given destination. Different types of proteins like secondary proteins and glycoproteins. Cell membrane protein lysosomal proteins all pass through Golgi Apparatus at some point of maturation. It is also used in the formation of complex sugars.

Ans. a) Storage of food

Food storage tissue

Explanation: They are referred to as food storage tissue, as their main function is to store and assimilate food. It aslo stores waste products of plants. While manufacturing of sugar and starch is done by tissues called collenchyma. Collenchyma also provides tensile strength and flexibility to the plants. While sclerenchyma provides mechanical strength to the plants.

Ans. d) Permanent tissues are Apical and intercalary is incorrect.

Explanation: A tissue that contains non dividing cells are known as permanent tissues. They are derived from meristematic tissues. Where Apical and Intercalary are meristems, these tissues are responsible for vertical growth of the plants. They are primary meristems, which are non-permanent tissues. Collenchyma is a support tissue of living elongated cells and irregular cell walls. It has thick deposits of cellulose in their cell walls making it thick at corners. Parenchyma tissue is the most common living tissue in plants. The most common function is storage of food and water in cells of root and stems. The intercellular space helps in gaseous exchange. Meristematic tissues lack vacuole in early stages.

Ans. b) Filamentous, presence of Cytoplasmic strands, presence of pyrenoids. 

Explanation: Characteristics of spirogyra 

With mucilaginous sheath they also have a multicellular filamentous body. They bear 2-10 ribbon shaped chloroplasts strands and spiral with many pyrenoids in their presence. Pyrenoids are found in chloroplast of algae and it is a non-membrane bound organelles. The cell walls consist of pectin and cellulose. The production of vegetative occurs under low temperatures. 

Ans. a) Pigeon

Explanation: The distinct characteristic feature of birds is, birds having hollow bones. Pneumatic bones are known as hollow bones. These bones increase buoyancy and reduce body weight. Due to hollow bones the weight of the bones is less, which indirectly helps birds to fly and pigeons are the birds. So, the answer A. Pigeon

Ans. c) Abuse of Analgesics

Explanation: Swelling in brain and liver caused by rare but dangerous conditions can be Reye’s Syndrome. When teenagers and children recovering viral infections like flu or chickenpox can be affected by Reye’s syndrome. Aspirin is a pain killer or analgesic. This is given to children or teenagers to recover from viral infection. The access use of Aspirin can lead to Reye’s syndrome.

Ans. b) Sneezing

Sneezing

Explanation: Upper respiratory tracts are lined with ciliated cells that secrete mucus. Foreign particles like dust and bacteria are trapped in the mucus. Due to the continuous beating of cilia helps to propel the material back into the nose and throat which can be expelled by coughing or sneezing. When the person is infected by viral infection or respiratory system disease more mucus is created and can contain infected viruses and bacteria. It can be spread by small droplets expelled during sneezing or coughing.

Ans. b) Skin cancer

Explanation: Harmful Ultraviolet (UV) rays from the sun are absorbed by the Ozone layer. Because of ozone layer depletion it causes increases in UV-B surface levels, which comes in direct contact with skin. Because of the direct contact it could lead to serious damage to the skin and can lead to skin cancer.

Ans. b) Increasing fertility of soil

Explanation: Rotation of crops helps the organic system to protect our environment. Changing the type of crop grown in one area on a regular basis is crop rotation. In organic farming an alternative group of plants like roots, cereals, brassicas, legumes etc are planted to increase the fertility of soil and to prevent pests and diseases from growing.

Ans. d) All the above

Example of Animal husbandry

Explanation: Animal husbandry is the management of farm animals. In this there is rearing of animals, feeding, breeding and caring of farm animals is done. It also includes grooming livestock which are raised to produce food and fibres like milk, eggs or meat. Proper breeding of domestic animals with desirable qualities helps in creation and maintaining a good generation of animals.

Ans. a) Natural material obtained by decaying plants and animal waste

Manure

Explanation: Manure is natural material obtained by decaying of plants and animal waste. To enhance the fertility of the soil manure is used. It is a natural and organic fertiliser. It usually consists of faeces and urine of domestic livestock, with or without litter such as hay, strew or bedding. The most common source of manure is from cows, sheep, horses, organic kitchen waste, dry leaves.