AP Inter 1st Year Botany Question Paper May 2016

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AP Inter 1st Year Botany Question Paper May 2016

Time: 3 Hours
Maximum Marks: 60

General Instructions:
Note : Read the following instructions carefully.

1. Answer all questions of Section ‘A’. Answer any six questions out of eight in Section ‘B’ and answer any two questions out of three in Section – ‘C’.
2. In Section ‘A’, questions from Sr. Nos. 1 to 10 are of “Very Short Answer Type”. Each question carries two marks. Every answer may be limited to five lines. Answer all the questions at one place in the same order.
3. In Section ‘B’, questions from Sr. Nos. 11 to 18 are of “Short Answer Type”. Each question carries four marks. Every answer may be limited to 20 lines.
4. In Section ‘C’, questions from Sr. Nos. 19 to 21 are of “Long Answer Type”. Each question carries eight marks. Every answer may be limited to 60 lines.
5. Draw labelled diagrams wherever necessary for questions in Section ‘B’and C.

Section – A (10 × 2 = 20)

Note : Answer all questions. Each answer may be limited to 5 lines.

Question 1.
Give the scientific name of Mango. Identify the generic name and specific epithet.
Answer:
Mangifera indica. Its generic name is Mangifera and specific epithet is ‘indica’.

Question 2.
What do the terms, physociont and mycobiont signify ?
Answer:
The algal component of lichen is called phycobiont. The fungal component of lichen is called mycobiont.

Question 3.
Who discovered the cell ? What was the book written by him ?
Answer:
‘Robert Hooke’ discovered the cell. ‘Micrographia’ was the book written by him.

Question 4.
What type of specialized roots are found in epiphytic plants ? What is their function ?
Answer:
In epiphytic plants, velamen roots are present. They help in absorption of moisture from atmosphere.

Question 5.
Name a plant that has a single fruit developing from the entire inflorescence. What is such a fruit called ?
Answer:
Pine apple. That fruit is called composite fruit.

Question 6.
What is natural system of plant classification ? Name the scientists who followed it.
Answer:
Plants are classified on the basis of all possible morphological character is called natural system of classification. It is followed by ‘BenthanY and ‘Hooker’.

Question 7.
Mention a single membrane bound organelle which is rich in hydrolytic enzymes.
Answer:
Lysosome.

Question 8.
What constituents of DNA are linked by glycosidic bonds ?
Answer:
Individual monosaccharides are linked by glycosidic bond.

Question 9.
An anther has 1200 pollen grains. How many pollen mother cells must have been there to produce them ?
Answer:
300 Pollen mother cells.

Question 10.
Name the type of land plants that can tolerate the salinities of the sea.
Answer:
The type of land plants that can tolerate the salinities of the sea are halophytes. Ex : Rhizophora.

Section – B (6 × 4 = 24)

Note : Answer any six questions. Each answer may be limited to 20 lines.

Question 11.
Give the Salient features and importance of chrysophytes.
Answer:

1. Chrysophytes includes diatoms and golden algae.
2. They are found in fresh water as well as in Marine water. Most of them are photosynthetic.
3. In Diatoms, the cell wall forms two thin overlapping shells (Epitheca over Hypotheca) which fit together as soap box.
4. The walls are embeded with silica and thus they are Industructable.
5. Daitoms leave large amounts of cell wall deposits in their habitat, this accumulation is referred as diatomaceous earth on ‘kiesulghur’.
6. They reproduce asexually by Binary fission and sexually by Gametes.

Importance:
1) The diatomaceous soil s used in polishing, filleration of oils and syrups.

Question 12.
Write a note on economic importance of Algae and Bryophytes.
Answer:
Economic importance of Algae :

1. A half of the carbon dioxide fixation is carried out by Algae through photosynthesis and increases the level of oxygen in the environment.
2. Many sps. of porphyra, Laminaria and Sargassum are used as food.
3. Some marine Brown algae and red algae produce large amounts of hydrocolloids like Algin and Carrageen.
4. Agar – Agar, a commercial product obtained from Gelidium and Gracilaria is used to grow microbes and also in the preparation of ice-creams and gellies.
5. Iodine is extracted from Laminaria.
6. Chlorella and Spirulina are used as food supplements even by space travelers.

Economic importance of Bryophytes :

1. Some mosses provide food for herbaceous mammals, birds and other animals.
2. Species of sphagnum. A moss provide peat used as fuel and because of its capacity to hold water as packing material for trans-shipment of living material.
3. Mosses along with lichens are the first organisms to colonise rocks.
4. Mosses form dense mats on the soil, thus prevents soil erosion.
5. They play a significant role in plant succession.

Question 13.
List the changes observed in angiosperm flower subsequent to pollination and fertilization.
Answer:

1. Calyx, Corolla, Stamens, style and stigma wither away.
2. Ovary develops into fruit.
3. Ovules develop into seeds.
4. The zygote develops into embryo.
5. Primary endosperm nucleus develops into endosperm.
6. The synergid and antipodals disintegrates.
7. Funicle of the ovule develops into stalk of the seed.
8. Integuments develop into seed coats.
9. Micropyle changes into seed pore.
10. Hilum changes into scar of the seed.

Question 14.
Describe the nonessential floral parts of plants belonging to Fabaceae.
Answer:
In Fabaceae, the nonessential floral parts are Calyx and Corolla.
Calyx : Sepals 5, gamosepalous, valvate aestivation and odd seapal is anterior.

Corolla : Petals 5, polypetalous, papilionaceous type consisting of large posterior petal called standard petal, two lateral petals called wings and the two anterior fused petals are called keel petals which enclose essential organs. They show descendingly imbricate aestivation.

Question 15.
Differentiate between Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER)
Answer:

Rough Endoplasmic Reticulum	Smooth Endoplasmic Reticulum
1. ER studded with ribosomes is called Rough ER.	1. ER without ribosomes is called Smooth ER.
2. These are mainly composed of cisternae.	2. These are mainly composed of tubules.
3. They are associated with nuclear membrane.	3. They are associated with plasma membrane
4. They mainly involved in Proteinsynthesis.	4. They mainly involved in in Lipid synthesis.

Question 16.
Though redundantly described as a resting phase, interphase does not really involve rest. Comment.
Answer:
The interphase also called phase of non apparent division though called the resting phase. It is the time during which the cell is preparing for divsion by undergoing cell growth and DNA replication. The interphase is divided into three further phases. They are a. G₁ phase, S-phse and G₂ phase.

a. G₁ Phase : It corresponds to the interval between mitosis and initiation of DNA replication. In this, the cell is metabolically active and grows continuously.
b. S-phase : DNA replication take place. The amount of DNA per cell doubles.
c. G2 phase: Proteinsynthesis continues. Cell organelles increases in number.”

Question 17.
What is periderm ? How does periderm formation take place in the dicot stem ?
Answer:
Phellogen, Phellem and Phelloderm together called periderm. In Dicots, stem continues to increase in girth due to activity of vscular cambium. As a result, the other cortical cells and epidermal layers ruptures and need to be replaced to provide new pulective layers. Hence another meinstematic layer develops in the cortical region called cork cambium or phellogen. It is made up of narrow, thin walled cells which cuts of cells in both sides. The outer cells differentiates into work or phellem, while the Inner cells differntiates into secondary cortex or phellodym. The work in imperious to water due to subain deposition in the cell Nail. The secondary cortical cells are parenchymatous. Phellogen, Phellem and phellodlum are collectively known as puiderm.

Question 18.
List the anatomical adaptations of hydrophytes.

1. Cuticle is totally absent in the submerged parts of the plants. If may be present, it is in the form of a thin film on the surface
2. The epidermis is composed of thin walled cells. They perform aborption and assimilation as all cells contain chloroplasts.
3. Stomata are totally absent in submerged hydrophytes as the gaseous exchange takes place by diffusion.
4. In Nymphaea, nelumbium, the leaves are epistomatous.
5. All hydrophytes contain aerenchyma that helps in gaseous exchange and buoyancy.
6. Mechanical tisssues are poorly developed.
7. Xylem is poorly developed.

Section – C (2 × 8 = 16)

Note : Answer any two questions. Each answer may be limited to 60 lines.

Question 19.
Explain how stem is modified variously to perform different functions.
Answer:
Stems are modified in several ways to perform different functions. They are :
1) Tendrils : Slender, spirally coiled structures which may develop either from auxiliary bud (cucumber) or from terminal bud (grapes) are called tendrils. They help in climbing.

2) Thorns : Buds are modified into woody, straight pointed thorns which protect plants from grazing animals.
Ex : Citrus, Bougain villaea.

3) Phylloclade : In some plants of acid zones, leaves are modified into scales or spines to reduce the rate of transpiration. In such plants, stems are modified into flattened, green structure which carryout photosynthesis. Such stems are called phylloclades.
Ex : In euphorbia stem is cylindrical, in casuarina needle like, and in opuntia – flattened, fleshy green.

4) Bulbils : In some plants, the vegetative buds or floral buds store food materials. At maturity, may detach from the parent plants, develop.adventitious roots, grow as new plants thus help in vegetative reproduction. Ex : Diascoria.

5) Underground stems : In some plants, stem grows into soil, store food materials, show perennation, to resist unfavourable conditions and also help in vegetative reproduction. Such stems are called underground stems.
Ex : Rhizome – Ginger, com – colacacia.

6) Sub aerial stems : In some plants, some part of the stem is underground and some part is aerial. Such stems are called sub aerial stems. In such plants, slender, lateral branches arises from the base of the main axis, grow vertically, arches downwards, produce adventitious roots when touches the ground. When they separates from the parent plant, they develop into new plants they help in vegetative reproduction.
Ex : Stolons – Nerium, Jasmine
Suckers – Chrysanthemum, Mertha.

Question 20.
Describe the process of fertilization in angiosperms.
Answer:
The fusion of male and female gametes is called fertilization.
The process of fertilization in angiosperms is described under the following five steps.

A) Entry of the pollen tube into the ovule : The pollen tube enters into the ovule in 3 ways.

1. Pologamy : Pollen tube enters into the ovule through microphyle. e.g. : Ottelia, Hibiscus.
2. Chalazogamy : Pollen tube enters into the ovule through chalaza. e.g. : Casiarina.
3. Mesogamy : Pollen tube enters into the ovule through integu-ments or funiculus, e.g. : Cucurbita.

B) Entry of pollen tube into the embryo sac : The pollen tube enters into the embryo sac only through the microphylar region either by destroying one of the synergids or in between egg cell and synergid. The entry of pollen tube is directed by filiform apparatus.

C) Dicharge of male gametes or sperms: After entry of pollen tube into the embryosac, the male gametes are liberated by one of the following ways.
a) Tip of the pollen tube may burst out
b) Degeneration of the tip of the pollen tube.
c) Formation of an apical pore at the tip of the pollen tube. The pollen tube finally releases the intact male gametes and vegetative nucleus.

D) Gametic Fusion : One of sperm nucleus [first sperm] fuses with egg cell and forms a dipliod zygote (2n). This fusion is called syngamy or fertilization. It was first discovered by Strasburger (1884).

E) Triple fusion and Double fertilization : The second sperm nucleus fuses with the secondary nucleus of the embryosac and forms Primary endosperm nucleus [PEN], This fusion is called as Triple fusion.

It was first observed by Nawaschin in Lilium and Fertillaria. In angiosperms the two male gametes release into the embryo sac take part in two fertilizations. The first sperm nucleus combines with egg cell to form zygote and the second sperm nucleus combines with secondary nucleus to form primary endosperm nucleus. With the occurrence of two fertili- zations, this phenomenon is, i.e., Double (fertilization) includes syngamy as well as triple fusion. It results in the formation of fertile endospermic seeds.

Question 21.
Describe the internal structure of a dicot root.
Answer:
A thin transerverse section of dicot root shows three parts namely
(i) Epidermis
(ii) Cortex and
(iii) stele.

(i) Epidermis – It is the outer most layers made of thin walled cells. Some cells protrude in the form of unicelluler root hairs. So called Epiblema. it protects the inner parts. Root hairs help in absorption of water from the soil.

(ii) Cortex – It consists of several layers of thin walled parenchyma cells with inter cellular spaces. The Innermost layer of cortex is called Endodermis. It comprises a single layer of barrel shaped cells without intercellular spaces. The tangential as well as the radial walls of Endoderm cells show suberin thickenings called casparian strips. Some cells opposite to protoxylem lack these strips. Some cells opposite to protoxylem lack these strips called passeage cells. They help in the movement of water and dissolved salts from cortex into xylem.

(iii) Stele : – It is the central part, consists of 4 layers.

(d) Pericycle : It is single layered, made of thin walled parenchyma cells, present next to endodermis. It produces lateral roots and become vascular cambium during secondary growth.

(e) Vascular Bundle : Xylem and phloem constitutes vascular Bundle. They are arranged on different radius (in alternate manner) so called Radial vascular Bundle, Xylem is exarch, where protoxylem is towards periphery and metaxylem is towards the center. Xylem is diarch to tetrach condition. Xylem helps in conduction of water and minerals and phloem helps in conduction of food materials.

(f) Medulla : It is absent or small, made of parenchyma cells. When present, it helps in the storage of food and water.