Cell Structure and Function
- Match the stages of meiosis in Column—I to their characteristic features in Column—II and select the correct option using the codes given below :Column—I: a. Pachytene; b. Metaphase I; c. Diakinesis; d. ZygoteneColumn—II: (i) Pairing of homologous ch… Answer: 4. (iii) (iv) (ii) (i) Each stage of meiotic prophase I has one signature event. Pachytene: crossing-over between non-sister chromat... 1
- During cell growth, DNA synthesis takes place in Answer: 4. S phase In the cell cycle, DNA replication happens in the S (synthesis) phase of interphase. G₁ is for cell growth and preparing... 1
- A cell organelle containing hydrolytic enzymes is Answer: 4. lysosome Lysosomes are membrane-bound sacs filled with hydrolytic enzymes (acid hydrolases) that digest proteins, lipids, carbohy... 1
- A non-proteinaceous enzyme is Answer: 1. ribozyme Almost all enzymes are proteins, but a few RNA molecules also act as catalysts. Ribozyme is a catalytic RNA (for example... 1
- A typical fat molecule is made up of : Answer: 2. One glycerol and three fatty acid molecules A triglyceride (typical fat) is formed by esterification of one glycerol with three f... 1
- Which of the following is not a characteristic feature during mitosis in somatic cells ? Answer: 4. Synapsis Synapsis (pairing of homologous chromosomes) occurs in prophase I (zygotene) of meiosis, not in mitosis. Spindle fibres,... 1
- A cell at telophase stage is observed by a student in a plant brought from the field. He tells his teacher that this cell is not like other cells at telophase stage. There is no formation of cell plate and thus the cell is containing more number of c… Answer: 2. Polyploidy Failure of cell plate formation in telophase (cytokinesis fails) leaves a cell with a doubled chromosome number. Cells... 1
- Which one of the following statements is wrong ? Answer: 4. Glycine is a sulphur containing amino acid. Glycine is the simplest amino acid, with H as its R group, and has no sulphur. The su... 1
- Which one of the following cell organelles is enclosed by a single membrane ? Answer: 3. Lysosomes Lysosomes are single-membrane sacs, so the answer is option 3. Mitochondria and chloroplasts are enclosed by a double m... 1
- Water soluble pigments found in plant cell vacuoles are : Answer: 4. Anthocyanins Anthocyanins are water-soluble pigments dissolved in the cell sap of vacuoles and give red, blue and purple colours... 1
- Spindle fibres attach on to : Answer: 2. Kinetochore of the chromosome Key idea: Spindle fibres attach to the kinetochore. The kinetochore is a disc-shaped protein struct... 1
- In meiosis crossing over is initiated at : Answer: 1. Pachytene Key idea: Crossing over takes place at pachytene. At pachytene (prophase I), recombination nodules form and the enzyme... 1
- Microtubules are the constituents of : Answer: 2. Spindle fibres, Centrioles and Cilia Key idea: Microtubules make up spindle fibres, centrioles (and basal bodies), and the axonem... 1
- The two polypeptides of human insulin are linked together by : Answer: 4. Disulphide bridges Key idea: Insulin has two chains, A (21 amino acids) and B (30 amino acids), held together by disulphide bridg... 1
- Mitochondria and chloroplast are :(a) semi-autonomous organelles.(b) formed by division of pre - existing organelles and they contain DNA but lack protein synthesizing machinery.Which one of the following options is correct ? Answer: 3. (a) is true but (b) is false. Key idea: Mitochondria and chloroplasts are semi-autonomous organelles. (a) True. They have their o... 1