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The Discovery of DNA: In 1869, Friedrich Miescher isolated a unique chemical substance from white blood cells called nuclein. Nuclein was found to have high phosphorus content and showed acidic properties, leading to its name nucleic acid. By the early 1900s, it was discovered that nuclein was a mixture of proteins and nucleic acids. There are two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). The development of the double-helix model helped further the understanding of DNA and its role in genetics. The Genetic Material is DNA: By the early 1900s, geneticists knew that genes controlled the inheritance of traits and were located on chromosomes composed mainly of DNA and proteins. Initially, geneticists thought that proteins were the genetic material that caused variations observed within species. It was thought that DNA was a small and simple molecule that varied little among species. However, over time, it was shown that DNA molecules are large and vary...

Q. 1 Multiple choice questions. 1. The number of nuclei present in a zygote is …… a. two b.one c. four d.eight ANS:  b. one  A zygote is formed when a sperm cell fertilizes an egg cell, resulting in the fusion of their nuclei. Therefore, a zygote has only one nucleus. 2. Which of these is the male reproductive organ in human? a. sperm b. seminal fluid c. testes d. ovary ANS: c. testes Th e testes are the male reproductive organs in humans. They produce sperm and the male hormone testosterone. 3. Attachment of embryo to the wall of the uterus is known as…….. a. fertilization b. gestation c. cleavage d. implantation ANS: d. implantation  Implantation is the process by which the fertilized egg attaches itself to the wall of the uterus and begins to develop into an embryo. 4. Rupturing of follicles and discharge of ova is known as .............. a. capacitation b. gestation c. ovulation d. copulation ANS; c. ovulation Ovulation is the process in which the follicles in the ov...

 1. Fill in the blanks and explain the statements. a. After complete oxidation of a glucose molecules, ---- --- --- number of ATP molecules are formed. b. At the end of glycolysis, ---- --- -- molecules are obtained. c. Genetic recombination occurs in ---- -- phase of prophase of meiosis-I. d. All chromosomes are arranged parallel to equatorial plane of cell in-- -- -- phase of mitosis. e. For formation of plasma membrane,--- --- --- molecules are necessary. f. Our muscle cells perform -- -- -- type of respiration during exercise. ANS:  a. After complete oxidation of a glucose molecule, 36-38 ATP molecules are formed. b. At the end of glycolysis, 2 molecules of pyruvate, 2 molecules of ATP, and 2 molecules of NADH are obtained. c. Genetic recombination occurs in the pachytene phase of prophase of meiosis-I. d. All chromosomes are arranged parallel to the equatorial plane of the cell in the metaphase phase of mitosis. e. For the formation of the plasma membrane, phospholipid ...

  Reproduction in Lower and Higher Plants revision notes Reproduction is important for continuation of species and life. There are two types of reproduction: asexual and sexual. Asexual reproduction produces genetically identical offspring without the fusion of gametes. Organisms can reproduce asexually through fragmentation, budding, spore formation, binary fission, conidia formation, and gemma formation. Fragmentation occurs when multicellular organisms break into fragments, which grow into new individuals. Budding is the most common method of asexual reproduction in unicellular organisms, where one or more outgrowths (buds) develop into new individuals. Spore formation occurs in Chlamydomonas through flagellated, motile zoospores that can grow independently into new individuals. Binary fission occurs in Chlorella, Diatoms, and Chlamydomonas. Conidia formation occurs in Penicillium. Gemma formation occurs in Marchantia. Vegetative Reproduction : Plants can reproduce asexually thr...