Biology Written Work Lesson 7,8 PDF

# Study Material for Public Exams Questions ## Part A ### Very Short Answer Questions (VSAQs) - **2 Marks** - **What is the material required to conduct an experiment regarding food movement in the esophagus?** - Cycle tube and potatoes with oil coating are the materials required to conduct...

# Study Material for Public Exams Questions ## Part A ### Very Short Answer Questions (VSAQs) - **2 Marks** - **What is the material required to conduct an experiment regarding food movement in the esophagus?** - Cycle tube and potatoes with oil coating are the materials required to conduct an experiment regarding food movement in the esophagus. - **Name the chemical which is used to test the action of saliva on flour?** - Iodine solution is used to test the action of saliva on flour. - **What happens if there is no mucus in the esophagus?** - Oesophageal walls loose the capacity of lubrication for passing food due to lack of secretion of mucus. As a result, the tissues in the inner oesophageal walls are damaged. Hence mucus should be secreted in the oesophagus to lubricate and protect the oesophageal walls from damage. ### Short Answer Questions (SAQs) - **4 Marks** - **What may happen if villi are absent in small intestine?** 1. Small intestine is a coiled and long tube like structured with many finger like projections. 2. The villi increase the surface area for absorption. Blood vessels and Lymph vessels are present in the form of a network in the villi. 3. Transport of the products of digestion from the intestine into blood is called absorption. 4. They help to take up maximum amount of digested food to be sent to various parts of the body through blood. 5. If villi are absent, absorption will not take place. - **What will happen if islets of Langerhans fail to function?** 1. Insulin may not be produced. 2. Human may suffer from diabetes. 3. Sugar level increases in blood. - **Why do you think the stomach is structured like a bag rather than a tube like esophagus?** 1. The food taken has to remain in the stomach for a long time. 2. So it has to be processed for proper digestion and absorption. 3. If it was like a tube it would just pass down without undergoing much changes. ## Long Answer Questions (LAQs) - **6 Marks** - **"Taste is connected to the tongue and palate". Write an activity to prove it and write your observations.** - **Aim:** To prove that palate plays a major role in recognizing taste. - **Apparatus:** Sugar crystals, Stop watch. - **Procedure:** 1. Place some sugar crystals on the tongue. 2. Keep your mouth open and see that the tongue should not touch the palate. 3. Record the time from the moment you placed the crystals on your tongue till you get the taste, by using stop watch. 4. Now repeat the test by placing the sugar crystals on your tongue and pressing against the palate. - **Observe the given flowchart and answer the following questions:** 1. Name the chromosomes that determine the sex of an individual. 2. Show given information in the form of Checker Board. 3. In this situation, which principle of Mendel is applicable? 4. "Mother determines the sex of the baby". Is this statement correct or not? Why? **Diagram:** (illustration of sex chromosomes and their transmission) **Answers:** **1. Name the chromosomes that determine the sex of an individual.** Allosomes are sex chromosomes that determine the sex of an individual. **2. Show given information in the form of Checker Board.** * A checker board is provided visually in the document that shows the transmission of chromosomes. **3. In this situation, which principle of Mendel is applicable?** Mendel's Law of Segregation is applicable because offspring receives its own pair of alleles from both parents. **4. "Mother determines the sex of the baby". Is this statement correct or not? Why?** No, the given statement is not correct. Because Male have one 'X' and one 'Y' chromosomes in their allosome cells. All the gametes in women have only 'X' chromosomes. If the sperm which carries X chromosome fertilizes the ovum, the resultant baby will have XX. So the baby will be a girl. If the sperm which carries Y chromosome fertilises the ovum, the resultant baby will have XY. So the baby will be a boy. By this we conclude that men play important role in determining the sex of offspring. - **Explain in brief any two Evidences of Evolution.** * The first evidence is **embryological evidence,** which is the study of the development of an organism from egg to adult stage. Remarkable similarities in the embryos of different animals from fish to man indicate common ancestry. * The second evidence is **paleontological evidence,** which refers to the study of fossils. Fossils provide a record of life on Earth and show how organisms have evolved over time. ## 4 Marks Questions - **Who discovered DNA? Write a short note on it?** 1. Francis Crick and James Watson discovered DNA in 1953. 2. DNA molecule looks rather like spiral stair case having a shape known as double helix. 3. The frame work of stair case consist of alternate sugar and phosphate groups and the steps which join the frame work together are the pairs of chemical compounds called bases. 4. They are adenine, guinine, thymine, and cytosine. - **What are the differences between monohybrid and dihybrid cross?** * A monohybrid cross involves the inheritance of a single trait, while a dihybrid cross involves the inheritance of two traits. * This difference can be seen in the number of alleles being considered, as well as the number of possible genotypes and phenotypes that result from the cross. ## Write the main points in the Darwin theory of evolution, in a nutshell. 1. Any group of population of an organism contains variations and not all members of group are identical 2. Variations are passed from parent to offspring through heredity. 3. The natural selection over abundance of offspring leads to a constant struggle for their survival in any population. 4. Individual organisms with variations that help them to survive and reproduce tend to live longer and have more offsprings than organisms with less useful feature. 5. The offsprings of survivors inherit the useful variations, and the same process happens with every new generation until the variation becomes a common feature. 6. As the environment changes, the organism within the environment adapts and changes to the new living conditions. 7. Over a long period of time, each species of organism can accumulate so many changes that it becomes a new species, similar to, but distinctly different from the original species. All species on the earth arise in this way. 8. Evolution is a slow and continuous process. ## Diagram Based Questions - **Which types of characters did Mendel select?** - Mendel selected only pure breed of characters. - **What type of seeds are produced in F1 generation?** - All yellow color seeds are produced. - **In F1 generation which type of pollination takes place?** - Only self pollination. - **What type of progeny would get in F2?** - 75% of yellow seeds and 25% of green seeds.