Exam: F.Y.BSc Semester – I Subject: Life Science Paper – II Date of Exam: 27th November 2017 Question Paper code: 12024 Q 1 (A). Fill in the blanks (5) 1. To provide energy to carry out life processes. 2. Autotropic 3. Nutritional Needs /Fuel for all cellular work/The organic raw materials for biosynthesis/Essential nutrients, substances such as vitamins that the animal cannot make for itself. 4. Glycogen 5. 20 Q 1 (B) Match the Columns (5) A B (1) femur (b) appendicular skeleton (2) Phloem (e) organic solute (3) blood (a) fluid connective tissue (4) Stomata (c) Transpiration (5) Hydra (f) water Q 1 (C) Define 1. Anaerobic means without air.Sometimes there is not enough oxygen around for animals and plants to respire, but they still need energy to survive. Instead they carry out respiration in the absence of oxygen to produce the energy they require, this is called anaerobic Respiration 2. Urecotelism: Insects,land snails, and many reptiles including birds excrete nitrogenous waste product in the form of uric acid which is insoluble in water ,such organisms are called urecotelic organisms 3. Breathing roots found in plants growing in scanty oxygen levels 4. Book lungs : These are the respiratory organs and are always in pairs. Each comprising of 100-130 leaflets arranged like leaves of the book. They are present in scorpions. 1 5. Malpigian tubules : these are long ,filamentous, thread like yellow coloured structures attached at the junction of midgut and handgut in cockroach and serves as an excretory organs. Q 1 (D) True or False 1. False 2. True 3. True 4. False 5. False Q 2. (a) Answer any one: (10) 1. What is nutrition ? Explain Heterotrophic nutrition using suitable examples? Heterotrophic nutrition is nutrition obtained by digesting organic compounds. Animals, fungi, and protists are unable to synthesize organic compounds to use as food. They are known as heterotrophs. Heterotrophic organisms have to acquire and take in all the organic substances they need to survive. All heterotrophs (except blood and gut parasites) have to convert solid food into soluble compounds capable of being absorbed (digestion). When the soluble products of digestion a of the organism where complex materials (assimilation) are broken down for the release of energy (respiration). All heterotrophs depend on autotrophs for their nutrition. The three main types of heterotrophic nutrition are: Holozoic nutrition: the word holozoic is made from two words- holo= whole and zoikos= animals and literally means animals which eat their food whole. Complex food is taken into a specialist digestive system and broken down into small pieces to be absorbed. This consists of 5 stages, ingestion, digestion, absorption, assimilation and egestion. E.g.: human Saprobiontic /saprotrophic nutrition: Organisms feed on dead organic remains of other organisms. Eg.: decomposers Parasitic nutrition: Organisms obtain food from other living organisms (the host), with the host receiving no benefit from the parasite. When a parasite is present inside the body of the host, it is known as an endoparasite. Generally endoparasites attack and live in an intestine of an organism whereas parasites such as mites and leeches attach themselves to the outside the host’s body. They are known as ectoparasites. They suck and feed on the blood of the host. E.g.: tapeworms Symbiotic nutrition: Certain plants live in close association with other plants for long periods and share and shelter. E.g.: fungi and algae, rizobium and leguminous plants. 2 2. Explain the types of complex tissues in plants. Complex Tissues: The complex tissues are composed of different types of cells performing diverse functions. These are of two types:- xylem and phloem. (i) Xylem: Structurally, xylem consists of both living and nonliving cells. Xylem consists of four elements: tracheids, vessels, xylem fibers and xylem parenchyma. Xylem A - Trachieds; B & C - Vessels Tracheids: Tracheids are elongated or tube-like dead cell with hard, thick and lignified walls. Their ends are tapering, blunt or chisel-like. Their function is conduction of water and providing mechanical support to the plant. Vessels: Vessel is long cylindrical, tube like structure with lignified walls and a wide central lumen. The cells are dead as these do not have protoplast. The cells are arranged in longitudinal series in which the partitioned walls (transverse walls) are perforated, so the entire structure looks-like a water pipe. Their main function is transport of water and minerals. It also provides mechanical strength. Xylem fibers: These cells are elongated, lignified and pointed at both the ends. A xylem fiber helps in conduction of water and nutrients from root to the leaf and provides mechanical support to the plant. 3 Xylem Parenchyma: The cells are living and thin walled. The main function of xylem parenchyma is to store starch and fatty substances. (ii) Phloem: Phloem consists of four types of elements – sieve tubes, companion cells, and phloem parenchyma and phloem fibers. Structure of Phloem Sieve tube: These are elongated, tube-like slender cells placed end to end. The transverse walls at the ends are perforated and are known as sieve plates. The main function of sieve tubes is translocation of food, from leaves to the storage organs of the plants. Companion Cells: These are elongated cells attached to the lateral wall of the sieve tubes. These are mostly found in angiosperms. Phloem Parenchyma: The phloem parenchymas are living cells which have cytoplasm and nucleus. Their function is to store food materials. Phloem fibers or bast fibers: Sclerenchymatous cells associated with primary and secondary phloem are commonly called phloem fibers. These cells are elongated, lignified and provide mechanical strength to the plant body. Q.2 (B) 1. Explain hormonal control of digestion? Hormonal control of digestion Gut hormones have a key role in controlling food intake and energy expenditure. The gut is the body’s largest hormone-producing organ, releasing more than 20 different peptide hormones, some of which target the brain to regulate appetite and influence the pleasure of eating. 4 Gut hormones The gut hormones work in association with the gut’s extensive nervous system (enteric nervous system) and play a co-ordinating role in the control of appetite, the digestion of food, the regulation of energy balance and the maintenance of blood glucose levels. The gut continuously sends information to the brain regarding the quality and quantity of the food that is consumed. The role that some of these hormones play is: Ghrelin is produced in the stomach, and its function is to tell the brain that the body has to be fed. It increases appetite. Gastrin is produced in the stomach when it is stretched. It stimulates the release of gastric juice rich in pepsin and hydrochloric acid. Secretin is produced in the duodenum and has the effect of stimulating the pancreas to produce alkaline secretions as well as slowing the emptying of the stomach. Cholecystokinin (CCK) is produced in the duodenum. It reduces appetite, slows down the emptying of the stomach and stimulates the release of bile from the gall bladder. Peptide YY (PYY) is produced in the last part of the small intestine known as the ileum as well as parts of the large intestine. It plays a role in slowing down the passage of food along the gut, which increases the efficiency of digestion and nutrient absorption after meal. Glucagon-like peptide 1 (GLP-1) is produced in the small intestine and colon and has multiple actions including inhibition of gastric emptying and appetite as well as the stimulation of insulin release. 5 2. What are insectivorous plants? Explain how they are adapted for the process of digestion. Insectivorous plants are plants that derive some of their nutrients from trapping and consumiing animals or protozoan. The benefit they derive from their catch varies considerably; in some species it might include a small part of their nutrient intake and in others it might be an indispensable source of nutrients. As a rule, however, such animal food, however valuable it might be as a source of certain critically important minerals, is not the plants' major source of energy, which they generally derive mainly from photosynthesis. Insectivorous plants might consume insects and other animal material trapped adventitiously, though most species to which such food represents an important part of their intake are specifically, often spectacularly, adapted to attract and secure adequate supplies. Their prey animals typically but not exclusively, comprise insects and other arthropods. Plants highly adapted to reliance on animal food use a variety of mechanisms to secure their prey, such as pitfalls, sticky surfaces, hair-trigger snaps, bladder-traps, entangling furriness, and lobster- pot trap mechanisms. Also known as carnivorous plants, they appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings. Insectivorous plants include the Venus fly trap, several types of pitcher plants, butterworths, sundews, bladderworts, etc. They exploit the prey organisms mainly in a mutualistic relationship with other creatures, such as resident organisms that contribute to the digestion of prey. In particular animal prey organisms supply carnivorous plants with nitrogen, but they also are important sources of various 6 other soluble minerals, such as potassium and trace elements that are in short supply in environments where the plants flourish. This gives them a decisive advantage over other plants, whereas in nutrient-rich soils they tend to be out- competed by plants adapted to aggressive growth where nutrient supplies are not the major constraints. Technically these plants are not strictly insectivorous, as they consume any animal that they can secure and consume; the distinction is trivial, however, because not many primarily insectivorous organisms exclusively consume insects.