2nd Year NotesBiology class 12th

2nd Year Biology Chapter 19 Growth Development

2nd Year Biology Chapter 19 Growth Development Question And Answer

Short And Simple Question And Answer

Q1. What are growing points?

Ans. Growing points are specific regions in higher plants where growth occurs, such as the shoot apex and root tip.

Q2. What is secondary growth?

Ans. Secondary growth is the increase in thickness of plants due to the growth of secondary tissues, like secondary xylem and phloem, by the intercalary or vascular cambium.

Q3. Name the factors influencing the rate of growth?

Ans. The rate of growth is influenced by various external factors like temperature, light, oxygen, and internal factors like hormones, water, and vitamins.

Q4. What is correlation in plant development?

Ans. Correlation in plant development refers to the reciprocal relationship between the growth of different organs in different directions, leading to the development of various plant parts.

Q5. What is embryology?

Ans. Embryology is the study of the growth and differentiation undergone by an organism from a single fertilized egg into a complex, independent living being.

Q6. What is discoidal cleavage in bird eggs?

Ans. Discoidal cleavage is a type of cell division that occurs in bird eggs, primarily at the surface of the yolk at the animal pole.

Q7. What role do cytokinins play in apical dominance? Ans. Cytokinins play a role in releasing lateral buds from apical dominance when applied directly to the inhibited bud.

Q8. What are negative physiological changes defined as?

Ans. Negative physiological changes are often associated with aging in the body.

Q9. What factors disturb the normal process of development?

Ans. Abnormalities inherited from parents, chromosome or gene-related abnormalities, environmental factors, and metabolic defects can disturb the normal process of development.

Q10. Define embryonic induction?

Ans. Embryonic induction refers to the influence of notochordal cells on ectodermal cells to become the nervous system during development.

Q11. Differentiate between growth and development?

Ans. Growth is the permanent increase in size, while development encompasses the progressive changes that occur before an organism reaches adulthood.

Q12. What is meristem?

Ans. Meristems are young tissues or cell populations in plants that have the potential to divide and contribute to growth.

Q13. What is open growth in plants?

Ans. Open growth in plants refers to the continuous addition of new organs like branches, leaves, and roots, enlarging from the tips of roots and shoots throughout the plant’s life.

Q14. What are Apical Meristems?

Ans. Apical meristems are found at the tips of roots and shoots and are responsible for extending the plant body, playing a key role in primary growth.

Q15. What are Intercalary Meristems?

Ans. Intercalary meristems are located at the bases of internodes in many plants and contribute to the production of leaves and flowers; they are temporary in nature.

Q16. What are Lateral meristems?

Ans. Lateral meristems are cylinders of dividing cells found in dicots and gymnosperms, such as vascular and cork cambium. They are involved in secondary growth and increasing stem and root diameter.

Q17. Define differentiation in plants?

Ans. Differentiation in plants refers to the process of forming specialized tissues.

Q18. What did Thimann and Skoog discover?

Ans. Thimann and Skoog discovered that apical dominance is caused by auxin diffusing from the apical bud.

Q19. Differentiate between inhibitory and compensatory effects of auxin?

Ans. Inhibitory effects of auxin from the apical bud inhibit the growth of lateral shoots or buds, while compensatory effects occur when removing the apex releases lateral buds from apical dominance.

Q20. What is the incubation temperature for chick eggs?

Ans. The incubation temperature for chick eggs in artificial incubators is usually maintained between 36-38 degrees Celsius, allowing the chick to complete development and hatch on the twenty-first day.

A21. Cleavage refers to a series of mitotic divisions in the early stages of embryo development.

Q22. Define Morula?

Ans. Morula is a rounded, closely packed mass of blastomeres formed during cleavage.

Q23. What is Blastula?

Ans. Blastula is the stage following the morula, characterized by the presence of a segmentation cavity or blastocoel.

Q24. What is blastoderm?

Ans. Blastoderm is the discoidal cap of cells located above the blastocoel.

Q25. What is the zone of junction in developing chick embryos?

Ans. The zone of junction is the marginal area of the blastoderm where cells remain attached to and closely adhere to the yolk.

Q26. Define Gastrulation?

Ans. Gastrulation is a process involving the movement and rearrangement of cells in the embryo.

Q27. Which two layers are formed from the blastoderm during gastrulation?

Ans. Gastrulation results in the formation of two layers: the upper epiblast and the lower hypoblast.

Q28. What is the area pellucida?

Ans. The area pellucida refers to the central cells of the blastoderm, which can be separated from the yolk, creating a translucent area.

Q29. What is the area opaca?

Ans. The area opaca is the peripheral part of the blastoderm where cells remain unseparated from the yolk.

Q30. What is the primitive streak in chick embryos?

Ans. The primitive streak is a midline thickening formed in chick embryos, where mesodermal cells migrate medially and caudally, representing the dorsal and lateral lips of the blastopore.

Q31. What is the primitive node?

Ans. The primitive node is an aggregation of notochordal cells located at the anterior end of the primitive streak.

Q32. What is Hensen’s node?

Ans. Hensen’s node is a local thickening at the cephalic end of the primitive streak in chick embryos.

Q33. What is the germ wall? Ans. The germ wall is the area where expanding germ layers merge with the underlying yolk in chick embryos.

Q34. What is the gastrocoele?

Ans. The gastrocoele is the cavity within the gastrula.

Q35. How many layers does the lateral plate mesoderm split into?

Ans. The lateral plate mesoderm splits into two layers: the somatic mesoderm and the splanchnic mesoderm, with a space between them.

Q36. What is the coelom?

Ans. The coelom is the cavity formed between the somatic and splanchnic mesoderm layers.

Q37. What is a Neurula?

Ans. The term “neurula” is used to describe the stage of development during the formation of the nervous system.

Q38. How is the neural plate formed?

Ans. The neural plate forms on the dorsal surface of the gastrula, becoming a band that thickens and develops into the neural plate.

Q39. What is the neurocoel?

Ans. The neurocoel is the cavity formed within the neural tube, which represents the central nervous system.

Q40. How is the neural tube formed in chick embryos?

Ans. The neural plate sinks and the neural folds grow toward each other, ultimately fusing in the mid-dorsal line to create the neural tube.

Q41. What are neuropores?

Ans. Neuropores are small openings at each end of the neural tube, known as the anterior and posterior neuropores, which later close.

Q42. What is the neurocoel?

Ans. The neurocoel is the cavity enclosed within the neural tube, representing the central nervous system.

Q43. What was Hans Dietrich’s work?

Ans. Hans Dietrich separated sea urchin eggs at the two-cell stage and observed that both halves developed into normal larvae, highlighting the concept of regulative development.

Q44. What is Acetabularia?

Ans. Acetabularia is a multicellular alga with a structure consisting of a rhizoid, a long stalk, and an umbrella-shaped cap at the top.

Q45. What is primary induction?

Ans. Primary induction refers to the role of the dorsal lip area as the primary organizer in inducing secondary embryo development in the host.

Q46. Define regeneration?

Ans. Regeneration is the ability of an organism to regrow or recover lost or injured body parts.

Q47. What are neoblasts?

Ans. Neoblasts are unspecialized cells found in flatworms like Planaria that can migrate to the site of amputation and differentiate into specialized cell types for regeneration.

Q48. Define abnormal development?

Ans. Abnormal development refers to the situation where certain body parts do not develop normally under unfavorable conditions.

Q49. Define Teratology?

Ans. Teratology is the branch of biology that deals with abnormal development and the causes behind such developments.

Q50. How is the normal process of development disturbed?

Ans. The normal process of development can be disturbed by factors such as abnormalities inherited from parents, chromosome or gene-related abnormalities, environmental factors, and metabolic defects.

Q51. What are Teratogens?

Ans. Teratogens are environmental factors that can cause or contribute to abnormal development, such as ionizing radiations like X-rays.

Q52. What is Microcephaly?

Ans. Microcephaly is a birth defect where individuals are born with a small skull.

Q53. What is Cleft palate?

Ans. Cleft palate is an abnormality where individuals have a split or opening in the upper lip or a harelip.

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