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Sunday, April 19, 2020

Lecture notes on flight adaptations in birds

Morpholgical,anatomical and physiological changes or developments in the organization of an animalwhich are suited to a particular environment is called adaptation.Birds are the masters of air whose bodies are highly specialized for aerial mode of life. In aerial birds every part of their body has been modified for aerial life. To fly in air, they have to possess following essential specializations in their morphology, anatomy and physiology

A. Morphological adaptations

1. Body shape : Because speed is a must for aerial life, so, to minimise the resistance offered by air during fight, the body of most birds is fusiform or spindle-shaped and it lacks any extra projection which may offer resistance in the attainment of speed in air.

2. Body-covering of feathers :Body is covered by special skin derivatives called feathers

(a).The smooth closely fitting and backwardly directed contour feathers make the body stream-lined and reduces the friction

(b) The feathery covering makes the body light and at the same time protects from the hazards of environmental temperature,

(d) The non-conducting covering of feathers insulates the body perfectly and prevents loss of heat to maintain a constant temperature.

(e) Feathers of wings form a broad surface for striking the air.

3. Organs for flight:The forelimbs have transformed into unique and powerful propelling organs, the wings. The wings are the sole organs of flight.

4. Mobile neck and beak : The transformation of forelimbs into wings is duly compensated by the extreme mobility of the long and flexible neck for reaching food.

5. Bipedal locomotion : As anterior part of the body of birds becomes concerned with flight, the posterior part of body becomes modified for movement on land.

6. Short tail : The short tail of a bird bears a tuft of longtail feathers or rectrices, which spread out in a fan-like manner and serve as a rudder during flight. They also assist in steering, lifting and counter-balancing during flying and perching.

B. Anatomical Volant Adaptations

Flying birds have following anatomical modifications for volant life :

1. Flight muscles: The action of the wings is controlled by the flight muscles which are greatly developed, weighing about one-sixth of the entire bird, while the muscles of the back remain greatly reduced. The muscle fibres comprising the flight muscles are of striated type and well vascularised to withstand fatigueless after prolonged activity. The wings are depressed by large muscles, pectoralis major and elevated by pectoralis minor. Other muscles are small and help the above muscles in their functioning.

2.Skeletal system

a. Preumatic bones- The bones are light, hollow and provide more space for muscles attachment. Due to pneumatic nature weight of the body is reduced which is helpful in flight.

b. Skull- Bones of skull are fused and light; teeth are absent in jaws. This reduce the weight of the body.

c. Fused thoracic vertebrae- The first four thoracic vertebrae are fused to form a firm fulcrum for working of the wing. In flightless birds these are free.

d.Synsacrum- Last thoracic, lumber sacral and caudal vertebrae fused to form synsacrum. Pelvic girdle & synsacrum provide plate like out come to support the weight of the body.

e. Sternum-Sternum is well developed and support the viscera. It also provide the surface for the attachment of flight muscles.

f. Pectoral girdle-It is strong. The coracoid is stout pillar like to resist the down stroke of the entire wing.The clavicle and interclavicles fused to forms v-shaped bone called, furcula which help in flying.

g. Pygostyle-The last four caudal vertebrae are fused to form the pygostyle which offer a strong attachment

to the rectrices.

h. Ribs with uncinate processes

3. Digestive system : The rate of metabolism in birds is very high, food requirements are great and digestion is rapid. Most birds are very selective in their diet and accordingly their beaks

are variously modified. Further, bécause undigested waste is minimum and is immediately got rid off, consequently the rectum becomes much reduced in length and never stores the undigested food. The ill-development of rectum of flying birds indicates towards the fact that the flying animals cannot afford to bear the weight of faeces.The absence of gall bladder to reduce weight.

4. Respiratory system : As a flying bird requires great and sustained power, therefore, its respiratory system remains specialized to meet the extensive rate of metabolism greater amount of oxygen molecules is needed by the body tissues. For this purpose, the dense,

inelastic and complicated lungs are supplemented by a remarkable

system of air sacs,, which grow out from lungs and occupy allavailable space between internal organs, even extending to the cavities of hollow bones. The air sacs primarily reduce the specific gravity of the bird and also facilitate complete aeration of the lungs. The avian lungs are aerated twice at each breath which is called double respiration. The air sacs help in regulating body temperature by internal perspiration.

5. Circulatory system : Rapid metabolism requires large oxygen supply to the tissues, which can be achieved by an efficient cireulatory system. powerful and efficient. Due 'to double circulation in it, the oxygenated and deoxygenated bloods remain completely separated.

Further, red blood cells of birds contains large amount of haemoglobin and this is responsible for blood's quick and perfect aeration.

6. Warm-bloodedness : In birds the body temperature remains high (40°-46°C) and does not change with the change of environmental temperature. The high and constant body temperature enables the bird to take flights at high altitudes and also facilitates activeness in every season.

7. Excretory systems: The avian excretory system becomes specialized in three ways : 1. For the retention of water, the uriniferous tubules of avian metanephric kidneys are added with Henle's loops, which are efficient in water absorption. coprodaeum of cloaca is another efficient water absorbing organ of birds. 2. For reducing the weight of body, there occurs no urinary bladder and the semi-solid urine is immediately excreted out, not retained for long in the body. 3. The metabolic nitrogenous wastes are converted into less toxic and insoluble organic

compounds such as uric acid and urates, which is an important physiological volant adaptation.

8. Brain and sense organs: The avian brain is highly developed consisting of well-developed centres of equilibrium, muscular coordination and instinct. Hence, the cerebellum and cerebrum are highly developed. Because birds have to depend mostly on the sense of sight, so, the eyes and optic lobes of brain are well developed.Presence of pecten in the eye for assisting vision.

9. Reproductive organs: In female birds the ovary and oviduct of one side (i.e., right side) of body are preserved. This necessarily reduces the weight of body.

Monday, April 6, 2020

CUET MSC ZOOLOGY OR ANIMAL SCIENCE ENTRANCE EXAM PRACTICE QUESTIONS

1. Maximum recombination frequency between two genes is-

(a) 25 % (b) 50 %

2. The distance between two base pairs in Watson-Crick B-DNA is

(a) 34 nm (b) 3.4 nm

3. The stage of meiosis I in which crossing over takes place

(a) Zygotene (b) Diplotene

4. Among the following which mutagen induces formation of thymidine dimmers in

DNA

(a) UV (b) Ethyl methyl sulphate

5. Na+ – K+ pump is-

(a) Symport system (b) Antiport system

6. Consider the following statements. Which is correct?

(a) Intracellular concentration of Na+ is always high

(b) Intracellular concentration of K+ ion is low

concentration

(d) Extra cellular concentration of Na+ and intracellular concentration of K+ is always

high in normal cell

7. Exrachromosomal inheritance can be detected by-

(a) Back cross (b) Test cross

8. Dosage compensation occurs in-

(a) Insects and mammals (b) Reptiles and mammals

9. Drosophilla with chromosome complement XXXXY/AA will be-

(a) fertile female (b) meta male

10. During fusion of Rat and Human cell it was found that chromosomes of one species

was selectively eliminated, this had opened new doors to study-

(a) Transgenic study

(b) Chromosomal incompatibility

(d) Dominance of genes

11. B and T-cells of immune system are activated by-

(a) T-cytotoxic cells (b) T-helper cells

12. Immunoglobulin playing role in allergic reaction

(a) IgG (b) IgM

13. A bacteria growing exponentially with doubling rate of 10 minutes. The intrinsic rate

of growth would be maximum when bacterial numbers are-

(a) at carrying capacity

(b) half of carrying capacity

(d) remains constant at all phases

14. The nutritional medium was supplied to growing bacteria. If whole nutrient get

depleted in 20 cycles, then stage at which the amount of nutrient was half used-

(a) At end of 10 cycle (b) At beginning of 19 cycle

15. Regarding gene expression in prokaryotes and Eukaryotes, which statement is correct-

(a) m-RNA and DNA are colinear

(b) m-RNA and protein synthesis can occur simultaneously

(d) RNA polymerase can bind to promoters situated upstream to gene

16. DNA fragment between size 2000 KD and 500 Kd can be separated using-

(a) PAGE (b) chromatography

17. The strongest evidence which suggest that RNA was ancient then DNA

(a) RNA can act as template for DNA synthesis

(b) RNA can work as catalyst

(d) RNA is genetic material in certain viruses

18. In an polypeptide if alanine is replaced by praline then-

(a) Its tendency to form á-helix increases

(b) Its tendency to form â-sheets increase

(d) There would no effect

19. Phosopho fructokinase is allosterically regulated by-

(a) ATP (b) ADP

20. cdK-2 exerts its effect during which stage of cell cycle

(a) G1 phase (b) S phase

21. Diploid maize have 10 pairs of chromosome. Number of chromosome at Metaphase-I

will be-

(a) 10 (b) 20

22. For an endothermic reaction to occur spontaneously the

(a) DG = 0 (b) DG > 0

23. Which enzyme is involved in detoxification reaction-

(a) glutathione oxidase (b) topoisomerase

24. The birds in tropics are generally smaller in size because of-

(a) To increase surface area to volume ratio

(b) To decrease surface area to volume ratio

(d) Aestivation

25. In an pond ecosystem, net productivity by zooplankton is ‘p’ and biomass consumed

by small fishes is ‘c’, then the ratio of c/p is termed as-

(a) Assimilation efficiency

(b) Net secondary productivity

(d) Conversion efficiency

26. For climax which statement is INCORRECT?

(a) Number of perennial species increases

(b) Dependency on detritious food chain increases

(d) Exploitation competition is more then normal competition

27. At present, the relationship between human and monkey can be stated as

(a) They both have common ancestors

(b) Human have evolved from monkey

(d) Relationship can not be established

28. Most of new species are formed by the process of –

(a) Anagenesis (b) Cladogenesis

29. The alternative pathway of respiration can be inhibited by

(a) Cyanide (b) SHAM

30. Dendrogram is-

(a) Arrangement of chromosomes

(b) graphical representation of phylogenetic tree

(d) evolutionary time scale representation

31. Development of sporophyte directly from gametes without fertilization is termed as-

(a) Apogamy (b) Apospory

32. Goblet cells are located in-

(a) Liver (b) Oesophagus

33. The phytohormone which provides desiccation resistance to embryo in germinating

seed is-

(a) Gibberlic Acid (b) Ethylene

34. Plants growing in cold environments generally have

(a) high cholesterol (b) high saturated fatty acid

35. Which is not true about TCA cycle-

(a) takes place in mitochondrial matrix

(b) Single largest source of direct ATP

(d) there is formation of NADPH and FADH

36. Which is correct relationship between habitat disturbance and biodiversity-

(a) Areas with no habitat disturbance tends to have high biodiversity

(b) Areas with high habitat disturbance tends to have high biodiversity

(d) Areas with no habitat disturbance tends to have low biodiversity

37. The probability of capturing an individual of certain species is Pi, then total biodiversity

can be represented as

(a) S(Pi)2 (b) 1 – S (Pi)2

38. Hardy Weinberg law operates on-

(a) Non-evolving population (b) Slow evolving population

39. If a gene have a three alleles namely p, q, r. Then Hardy- Weinberg law can be

represented as-

(a) (p + q + r)² (b) (p + q + r)³

40. In a graph population density is plotted on X-axis then what should be plotted on

Y-axis to get a bell shape curve

(a) dN/dt (b) 1 – dN/dt

41. In an organism G + C content is 50 %. What is probability of matching 6 nucleotide

sequence in genome

(a) (0.25)4 (b) (0.25)5

42. The bacteria which are classified on basis of morphology are-

(a) Spore forming bacteria

(b) non-sporulating bacteria

(d) anaerobic bacteria

43. Among the following which groups do not obey Linneus Nomenclature?

(a) Virus (b) Bacteria

44. ICBN stands for

(a) International Code for Botanical Nomenclature

(b) International Code for Biological Nomenclature

(d) International Code for Binomial Nomenclature

45. The differences in chromosome morphology between different species can be compared

(a) chromosome banding

(b) Tritium Hydrogen labeling

(d) in-situ hybridization

46. Typical mendelian dihybrid ratio for F2 generation is-

(a) 9:3:3:1 (b) 9:7

47. Smallest unit which can evolve is-

(a) Individual (b) Species

48. Nerves are connected to each other by

(a) hormone (b) neurotransmitter

49. Endocrine signaling is analogous to-

(a) Making a telephone call (b) Radio transmission

50. Examples of connective tissue are

(a) Bone and muscle (b)Muscle and Blood

ANSWER KEY
1. Maximum recombination frequency between two genes is-

(a) 25 % (b) 50 %

2. The distance between two base pairs in Watson-Crick B-DNA is

(a) 34 nm (b) 3.4 nm

(c) 0.34 nm (d) 0.034 nm

3. The stage of meiosis I in which crossing over takes place

(a) Zygotene (b) Diplotene

4. Among the following which mutagen induces formation of thymidine dimmers in

DNA

(a) UV (b) Ethyl methyl sulphate

5. Na+ – K+ pump is-

(a) Symport system (b) Antiport system

(c) ABC transporter (d) Diffusion pump

6. Consider the following statements. Which is correct?

(a) Intracellular concentration of Na+ is always high

(b) Intracellular concentration of K+ ion is low

concentration

(d) Extra cellular concentration of Na+ and intracellular concentration of K+ is always

high in normal cell

7. Exrachromosomal inheritance can be detected by-

(a) Back cross (b) Test cross

(c) Reciprocal cross (d) Dihybrid cross

8. Dosage compensation occurs in-

(a) Insects and mammals (b) Reptiles and mammals

9. Drosophilla with chromosome complement XXXXY/AA will be-

(a) fertile female (b) meta male

10. During fusion of Rat and Human cell it was found that chromosomes of one species

was selectively eliminated, this had opened new doors to study-

(a) Transgenic study

(b) Chromosomal incompatibility

(c) Gene and linkage mapping

(d) Dominance of genes

11. B and T-cells of immune system are activated by-

(a) T-cytotoxic cells (b) T-helper cells

12. Immunoglobulin playing role in allergic reaction

(a) IgG (b) IgM

13. A bacteria growing exponentially with doubling rate of 10 minutes. The intrinsic rate

of growth would be maximum when bacterial numbers are-

(a) at carrying capacity

(b) half of carrying capacity

(d) remains constant at all phases

14. The nutritional medium was supplied to growing bacteria. If whole nutrient get

depleted in 20 cycles, then stage at which the amount of nutrient was half used-

(a) At end of 10 cycle (b) At beginning of 19 cycle

(c) At end of 19 cycle (d) At end of 11 cycle

15. Regarding gene expression in prokaryotes and Eukaryotes, which statement is correct-

(a) m-RNA and DNA are colinear

(b) m-RNA and protein synthesis can occur simultaneously

(d) RNA polymerase can bind to promoters situated upstream to gene

16. DNA fragment between size 2000 KD and 500 Kd can be separated using-

(a) PAGE (b) chromatography

17. The strongest evidence which suggest that RNA was ancient then DNA

(a) RNA can act as template for DNA synthesis

(b) RNA can work as catalyst

(d) RNA is genetic material in certain viruses

18. In an polypeptide if alanine is replaced by praline then-

(a) Its tendency to form á-helix increases

(b) Its tendency to form â-sheets increase

(d) There would no effect

19. Phosopho fructokinase is allosterically regulated by-

(a) ATP (b) ADP

20. cdK-2 exerts its effect during which stage of cell cycle

(a) G1 phase (b) S phase

21. Diploid maize have 10 pairs of chromosome. Number of chromosome at Metaphase-I

will be-

(a) 10 (b) 20

22. For an endothermic reaction to occur spontaneously the

(a) DG = 0 (b) DG > 0

(c) DG < 0 (d) independent of DG

23. Which enzyme is involved in detoxification reaction-

(a) glutathione oxidase (b) topoisomerase

24. The birds in tropics are generally smaller in size because of-

(a) To increase surface area to volume ratio

(b) To decrease surface area to volume ratio

(d) Aestivation

25. In an pond ecosystem, net productivity by zooplankton is ‘p’ and biomass consumed

by small fishes is ‘c’, then the ratio of c/p is termed as-

(a) Assimilation efficiency

(b) Net secondary productivity

(c) Consumption efficiency

(d) Conversion efficiency

26. For climax which statement is INCORRECT?

(a) Number of perennial species increases

(b) Dependency on detritious food chain increases

(d) Exploitation competition is more then normal competition

27. At present, the relationship between human and monkey can be stated as

(a) They both have common ancestors

(b) Human have evolved from monkey

(d) Relationship can not be established

28. Most of new species are formed by the process of –

(a) Anagenesis (b) Cladogenesis

29. The alternative pathway of respiration can be inhibited by

(a) Cyanide (b) SHAM

30. Dendrogram is-

(a) Arrangement of chromosomes

(b) graphical representation of phylogenetic tree

(c) taxonomic key to establish relationship

(d) evolutionary time scale representation

31. Development of sporophyte directly from gametes without fertilization is termed as-

(a) Apogamy (b) Apospory

32. Goblet cells are located in-

(a) Liver (b) Oesophagus

33. The phytohormone which provides desiccation resistance to embryo in germinating

seed is-

(a) Gibberlic Acid (b) Ethylene

34. Plants growing in cold environments generally have

(a) high cholesterol (b) high saturated fatty acid

(c) high unsaturated fatty acid (d) short chain fatty acids

35. Which is not true about TCA cycle-

(a) takes place in mitochondrial matrix

(b) Single largest source of direct ATP

(c) is linked to glycolysis via pyruvate

(d) there is formation of NADPH and FADH

36. Which is correct relationship between habitat disturbance and biodiversity-

(a) Areas with no habitat disturbance tends to have high biodiversity

(b) Areas with high habitat disturbance tends to have high biodiversity

(c) Areas with moderate habitat disturbance tends to have high biodiversity

(d) Areas with no habitat disturbance tends to have low biodiversity

37. The probability of capturing an individual of certain species is Pi, then total biodiversity

can be represented as

(a) S(Pi)2 (b) 1 – S (Pi)2

38. Hardy Weinberg law operates on-

(a) Non-evolving population (b) Slow evolving population

39. If a gene have a three alleles namely p, q, r. Then Hardy- Weinberg law can be

represented as-

(a) (p + q + r)² (b) (p + q + r)³

40. In a graph population density is plotted on X-axis then what should be plotted on

Y-axis to get a bell shape curve

(a) dN/dt (b) 1 – dN/dt

41. In an organism G + C content is 50 %. What is probability of matching 6 nucleotide

sequence in genome

(a) (0.25)4 (b) (0.25)5

(c) (0.25)6 (d) (0.25)7

42. The bacteria which are classified on basis of morphology are-

(a) Spore forming bacteria

(b) non-sporulating bacteria

(d) anaerobic bacteria

43. Among the following which groups do not obey Linneus Nomenclature?

(a) Virus (b) Bacteria

44. ICBN stands for

(a) International Code for Botanical Nomenclature

(b) International Code for Biological Nomenclature

(d) International Code for Binomial Nomenclature

45. The differences in chromosome morphology between different species can be compared

(a) chromosome banding

(b) Tritium Hydrogen labeling

(d) in-situ hybridization

46. Typical mendelian dihybrid ratio for F2 generation is-

(a) 9:3:3:1 (b) 9:7

47. Smallest unit which can evolve is-

(a) Individual (b) Species

(c) population (d) cell

48. Nerves are connected to each other by

(a) hormone (b) neurotransmitter

49. Endocrine signaling is analogous to-

(a) Making a telephone call (b) Radio transmission

50. Examples of connective tissue are

(a) Bone and muscle (b)Muscle and Blood

(c) Bone and cartilage (d) Blood and skin

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Sunday, April 19, 2020

Lecture notes on flight adaptations in birds

Monday, April 6, 2020

CUET MSC ZOOLOGY OR ANIMAL SCIENCE ENTRANCE EXAM PRACTICE QUESTIONS

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