2.4 Fertilization.pdf

HSNC BOARD's SMT CHANDIBAI HIMATHMAL MANSUKHANI COLLEGE ULHASNAGAR - 3 MODULE 2: LIFE PROCESSES-II 2.4 FERTILIZATION 2.4.1 EXTERNAL AND INTERNAL FERTILIZATION 2.4.2 OVIPARITY, 2.4.3. VIVIPARITY 2.4.4 OVO-VIVIPARITY ...

HSNC BOARD's SMT CHANDIBAI HIMATHMAL MANSUKHANI COLLEGE ULHASNAGAR - 3 MODULE 2: LIFE PROCESSES-II 2.4 FERTILIZATION 2.4.1 EXTERNAL AND INTERNAL FERTILIZATION 2.4.2 OVIPARITY, 2.4.3. VIVIPARITY 2.4.4 OVO-VIVIPARITY  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Fertilization is the process where the male gamete (sperm) and female gamete (egg/ovum) fuse to form a zygote, which develops into an embryo. Fertilization can occur in two ways, depending on the species: external fertilization and internal fertilization. 1. External Fertilization In external fertilization, fertilization takes place outside the female’s body, typically in water or moist environments. The female lays eggs, and the male releases sperm over the eggs in the external environment to achieve fertilization. This type of fertilization is common in aquatic animals, including most fish, amphibians, and some invertebrates like molluscs. Advantages: A large number of offspring can be produced at once. Less energy is spent in the process of copulation or internal reproductive structures. Disadvantages: Eggs and sperm are exposed to environmental hazards such as predators, temperature fluctuations, or water currents, which reduce the chances of successful fertilization. Fertilization success is dependent on timing and environmental conditions. Examples: Fish and amphibians: Many species of fish and frogs release sperm and eggs into the water, where fertilization occurs. Coral spawning: Corals release both sperm and eggs into the ocean, where they drift in the water and fertilization happens externally.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Internal Fertilization In internal fertilization, fertilization takes place inside the female’s body. The male deposits sperm into the female's reproductive tract through copulation, and the sperm travels to the egg for fertilization. This method is typical of terrestrial animals such as mammals, reptiles, birds, and some species of amphibians. Advantages: Higher chances of successful fertilization since sperm and egg are protected within the female’s body. Offspring are more protected during development, reducing the risk of predation and environmental hazards. Disadvantages: Fewer offspring are produced at a time. It requires more complex reproductive structures and behaviours. Energy investment in finding mates and ensuring successful copulation is higher. Examples: Mammals: Fertilization occurs in the female reproductive tract, often in the fallopian tubes. Reptiles and birds: The sperm is deposited into the female’s reproductive tract during copulation, leading to fertilization.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Oviparity, Viviparity, Ovoviviparity These terms describe the different methods of reproduction and embryonic development based on how and where the developing embryo is nurtured, either inside or outside the mother's body. 1. Oviparity Oviparous animals lay eggs that develop and hatch outside the mother’s body. Fertilization can be either internal or external, but embryonic development occurs entirely outside the female body. The eggs have protective coverings like shells (in birds, reptiles) or jelly-like substances (in amphibians, fish) that help protect the developing embryo. The developing embryo gets nourishment from the yolk inside the egg. Examples: Birds: Birds lay eggs with hard, calcified shells. Reptiles: Snakes and turtles lay leathery-shelled eggs. Amphibians and Fish: Frogs and many fish lay gelatinous eggs in water. Advantages: Less energy is spent on prolonged internal gestation. Parents can lay many eggs, increasing the chance of survival. Disadvantages: Eggs are exposed to environmental dangers like predators, harsh weather, or infections.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Oviparity, Viviparity, Ovoviviparity 2. Viviparity In viviparous animals, the embryo develops inside the mother’s body, and the offspring are born alive. The developing embryo is nourished by the mother, typically via a placenta or other specialized structures, and remains in the mother until a more advanced stage of development. Internal fertilization is essential for viviparity, and the young are usually more developed and have a higher chance of survival when born. Examples: Mammals: Humans, cows, and most other mammals are viviparous, where the placenta provides nourishment to the developing fetus. Some sharks: Some species of sharks, like the hammerhead and great white, give birth to live young. Advantages: Higher survival rates due to protection and nourishment inside the mother’s body. Offspring are more developed and better equipped to survive in their environment at birth. Disadvantages: Requires significant maternal energy and investment. Fewer offspring are produced at a time, limiting reproductive success in dangerous or unpredictable environments.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Oviparity, Viviparity, Ovoviviparity 3. Ovoviviparity Ovoviviparous animals produce eggs, but these eggs develop inside the mother’s body, and the young are born alive when ready. Unlike viviparous animals, the embryo in ovoviviparous animals is not directly nourished by the mother but instead relies on the yolk sac of the egg for nutrition. The developing embryo is protected inside the mother, and the young hatch from the eggs while still within the mother’s body or shortly after being laid. Examples: Certain reptiles: Some species of snakes, like the boa constrictor, are ovoviviparous. Sharks: Some species of sharks, such as the sand tiger shark, are ovoviviparous. Fish: Some bony fish, such as guppies, are ovoviviparous. Advantages: The developing young are protected from predators and environmental hazards while still inside the mother. They are more developed when born, increasing survival rates. Disadvantages: Maternal energy is still required, though less than in fully viviparous species. Limited space in the mother restricts the number of offspring produced.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Summary External Fertilization occurs outside the body (common in aquatic species), while Internal Fertilization takes place inside the female’s body (typical of terrestrial species). Oviparity involves laying eggs that develop outside the mother's body (birds, reptiles), whereas Viviparity results in live birth with the embryo developing internally (mammals). Ovoviviparity is a combination where eggs develop inside the mother, but the young are born alive (some reptiles, fish, and sharks). These reproductive strategies reflect adaptations to different environmental and biological needs, each offering its advantages and challenges.  NOTES FERTILIZATION: EXTERNAL AND INTERNAL  NOTES FERTILIZATION: EXTERNAL AND INTERNAL  NOTES FERTILIZATION: EXTERNAL AND INTERNAL Oviparity, Viviparity, Ovoviviparity  NOTES EXAMINATION QUESTIONS 1. Describe the process of internal fertilization. How does it provide an advantage to terrestrial organisms compared to external fertilization? 2. Explain the stages of oogenesis and discuss how it differs from spermatogenesis. 3. Compare and contrast oviparity, viviparity, and ovoviviparity concerning embryonic development, parental care, and examples from the animal kingdom. 4. Describe the structure of a mammalian sperm and explain how each part is adapted to its function in fertilization. 5. Discuss the evolutionary significance of viviparity in mammals. What advantages and challenges does this reproductive strategy present? 6. Define external fertilization. Provide two examples of organisms that use this method. 7. Explain the stages of spermatogenesis. How do the structure and function of sperm change during this process? Short Answer Questions: 1. What is the role of the placenta in viviparous animals? 2. Explain the difference between internal and external fertilization. 3. Describe the process of spermatogenesis. 4. What is the significance of the acrosome in spermatozoa? 5. How does the zona pellucida contribute to fertilization in mammals? 6. State the difference between oviparous and viviparous animals. Provide one example for each. 7. What is ovoviviparity? Give two examples of organisms that reproduce this way. 8. Why is genetic diversity higher in sexual reproduction compared to asexual reproduction? 9. How is the mammalian ovum different from the sperm in terms of structure and function?  NOTES EXAMINATION QUESTIONS Multiple Choice Questions (MCQs): What type of fertilization occurs when sperm fertilizes an egg outside the female’s body? a) Internal fertilization b) External fertilization (Correct Answer) c) Viviparity d) Oviparity Which of the following is a characteristic of internal fertilization? a) Fertilization occurs in water b) Sperm and egg unite outside the female body c) The embryo develops inside the female's reproductive tract (Correct Answer) d) Eggs are laid in a gelatinous mass In oviparous animals, where does the embryo develop? a) Outside the female's body in eggs (Correct Answer) b) Inside the female's body c) Inside a placenta d) In the mother’s abdominal cavity Which reproductive strategy involves live birth but with embryos that rely on yolk rather than maternal nutrients? a) Oviparity b) Viviparity c) Ovoviviparity (Correct Answer) d) External fertilization What is the primary advantage of viviparity for offspring? a) Increased energy expenditure for the mother b) Offspring are less developed at birth c) Higher survival rates due to protection during development (Correct Answer) d) Greater number of offspring produced Which of the following is an example of an oviparous organism? a) Most mammals b) Some reptiles and birds c) Most fish (Correct Answer) d) Some sharks  NOTES EXAMINATION QUESTIONS Multiple Choice Questions (MCQs): In external fertilization, how do animals usually synchronize their reproductive activities? a) By physical contact b) Through environmental cues such as temperature c) By timing their spawning events (Correct Answer) d) By migrating together What is the primary disadvantage of external fertilization? a) Increased risk of egg and sperm being lost to predation (Correct Answer) b) Requires more energy for the female c) Offspring are often more developed d) Limited to aquatic environments Which of the following is a common feature of viviparous animals? a) Development of the embryo inside the mother (Correct Answer) b) Laying eggs c) Fertilization occurs in water d) Lack of parental care What happens during ovoviviparity? a) Eggs are fertilized externally and hatch outside b) Eggs develop inside the mother, but the young are nourished by the yolk (Correct Answer) c) Live young are born without eggs d) Embryos are attached to a placenta for nourishment  NOTES EXAMINATION QUESTIONS Multiple Choice Questions (MCQs): Which type of reproduction involves a single parent? a) Sexual reproduction b) Asexual reproduction (Correct Answer) c) External fertilization d) Internal fertilisation How does Paramecium reproduce asexually? a) Budding b) Binary fission (Correct Answer) c) Regeneration d) Gemmule formation What is a gemmule in sponges? a) A reproductive structure used for survival in harsh conditions (Correct Answer) b) A structure for feeding c) A method of sexual reproduction d) A form of locomotion What process does Hydra use for asexual reproduction? a) Binary fission b) Budding (Correct Answer) c) Regeneration d) Gemmule formation Which organism is known for its ability to regenerate lost body parts? a) Hydra b) Planaria (Correct Answer) c) Paramecium d) Sponge  NOTES EXAMINATION QUESTIONS Multiple Choice Questions (MCQs): How many parents are required for sexual reproduction? a) One b) Two (Correct Answer) c) Three d) None What is gametogenesis? a) The process of forming gametes (sperm and eggs) (Correct Answer) b) The process of cell division c) The process of fertilization d) The process of binary fission Which structure surrounds the mammalian ovum? a) Acrosome b) Blastula c) Zona pellucida (Correct Answer) d) Epididymis Which part of the mammalian sperm contains enzymes to penetrate the egg? a) Midpiece b) Tail c) Acrosome (Correct Answer) d) Nucleus What is fertilization? a) The fusion of sperm and egg (Correct Answer) b) The division of cells c) The growth of an embryo d) The formation of gametes  NOTES EXAMINATION QUESTIONS Multiple Choice Questions (MCQs): Where does external fertilization typically occur? a) In water (Correct Answer) b) On land c) Inside the female body d) In the air Which type of fertilization occurs inside the female’s body? a) External fertilization b) Internal fertilization (Correct Answer) c) Budding d) Fission Which animals lay eggs, and the embryos develop outside the mother’s body? a) Viviparous b) Oviparous (Correct Answer) c) Ovoviviparous d) Asexual In which type of reproduction do animals give birth to live young? a) Oviparity b) Ovoviviparity c) Viviparity (Correct Answer) d) Budding Which reproductive strategy involves eggs developing inside the mother, but without maternal nourishment? a) Oviparity b) Ovoviviparity (Correct Answer) c) Viviparity d) Binary fission