9th
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- Why it is necessary for people to have their blood examined before their marriage? It is necessary for people to have their blood examined before their marriage because genetic disorders are mainly transmitted through the r... 2
- Explain the structure, function and types of RNA. Answer: RNA (ribonucleic acid) is usually a single-stranded nucleic acid made of ribonucleotides; its main job is protein synthesis. Its thr... 1
- Explain your opinion about the DNA fingerprinting. DNA fingerprinting is the technique in which the sequence of the genes in the DNA of a person, i.e., the genome of the person is identified.... 1
- Describe the structure of DNA molecule. Answer: DNA is a double helix made of two long strands of nucleotides, twisted around each other like a spiral ladder (Watson and Crick mode... 1
- What is mean by chromosome? Explain its types. The structure in the nucleus of cells which carries hereditary characteristics is called as chromosome which is mainly made up of nucleic ac... 1
- Is it right to avoid living with a person suffering from a genetic disorder? No, it is not right to avoid living with a person suffering from a genetic disorder. Genetic disorders are transmitted from parents to offsp... 1
- Distinguish between monohybrid and dihybrid cross. Monohybrid cross Dihybrid cross (i) Cross involving a single pair of contrasting characters is called monohybrid cross. (i) Cross involving... 1
- Explain Mendel’s dihybrid ratio with any one of the cross. Answer: In a dihybrid cross, the F2 generation shows the phenotypic ratio 9 : 3 : 3 : 1. A dihybrid cross studies two pairs of contrasting c... 1
- a) Explain Mendel’s monohybrid progeny with the help of any one cross. Answer: In a monohybrid cross between pure tall (TT) and pure dwarf (tt) pea plants, all F1 plants are tall, and the F2 generation shows tal... 1
- Complete the following sentences by choosing the appropriate words from the brackets. a) Hereditary characters are transferred from parents to offspring’s by gene hence they are said to be structural and functional units of he... 1
- Explain co-ordination in plants with the help of suitable examples. Answer: Plants have no nervous system; they co-ordinate their responses through plant hormones (phytohormones) and through movements in resp... 1
- Explain the difference between the excretory system of humans and plants. Excretory system of humans excretory system of Plants 1. The excretory products of humans are toxic. They are harmful if stored in the body.... 1
- Explain chemical co-ordination in humans and give the names and functions of some hormones. Answer: Chemical co-ordination in humans is carried out by hormones secreted by endocrine (ductless) glands directly into the blood, which c... 1
- write note on Reflex action Reflex action is an immediate and involuntary response given to a stimulus from the environment. The reflex action is so spontaneous that it d... 1
- write notes on Human brain Human brain is highly evolved organ. It is the main controlling centre of nervous system. It is the part of the central nervous system. It i... 1
- write notes on nerve cell Nerve cell- Nerve cells are also known as neurons. Neurons or nerve cells are structural and functional units of the nervous system that car... 1
- write notes on Transpiration There are stomata on the leaves of the plants. Through these opening the excess of water is thrown out in the form of water vapours. This pr... 1
- Write notes on Root pressure The pressure created in the root cells is called a root pressure. Root cells are in contact with water and minerals in the soil. But the con... 1
- Complete the paragraph. The milk was on the stove. The milk was on the stove. Rasika was engrossed watching television. She smelled something burning. She ran towards the kitchen. The milk wa... 1
- Match the pairs and explain. ‘A’ ‘B’ 1. Growth of pollen tube towards ovule b. Chemotropic movement 2. Growth of shoot system c. Phototropic movement 3. Growth of root s... 1
- write harmfull effect of Deodorant It contains aluminium – zirconium compounds which are the most harmful chemicals in the deodorant. They can result in the development of dis... 1
- Write the harmful effects Radioactive substances Radioactive substances affect the central nervous system. Exposure to radioactive radiations for long periods can lead to hereditary defects... 1
- Write the harmful effects Artificial food colour Colours used in pickles, jam and sauces contain lead and mercury in small quantities. Regular consumption of these products can be dangerous... 1
- Write the harmful effects Artificial dye Use of dye for dyeing hair can have adverse effects like hair fall, damage to hair texture, burning of skin. The dyes used for dyeing hair h... 1