Copy of Life Sciences Reproduction in vertebrates 22 February 2024.pptx

Reproduction in vertebrates

1. LIFE SCIENCES GRADE 12 TOPIC: REPRODUCTION IN VERTEBRATES PRESENTERS : VEDIKA MAHARAJ AND AGNES MOABELO DATE: 22 FEBRUARY 2024

2. IMPORTANT DOCUMENTS RESOURCES Mind the Gap SSIP material DBE Study guides Broadcasting & WEB lessons Past year papers: NSC + Prelim Exemplar 4 sets Exam Guidelines & Textbooks www.education.gov.za

3. EXAM GUIDELINE REPRODUCTION IN VERTEBRATES PAPER 1: 8 MARKS

4. REPRODUCTION IN VERTEBRATES (8 marks) What to focus on: External and Internal fertilisation Precocial and Altricial development Parental care Amniotic Egg Ovipary, Vivipary and Ovovivipary

5. EXTERNAL FERTILISATION: ADVANTAGES & DISADVANTAGES No additional energy is needed for parental care or formation of a protective layer. No need for a male to have a special organ to insert the sperm into the female’s body. Chances of fertilisation are enhanced by courtship display by fish. Chances are very slim for a sperm cell to meet the ova. Predators eat the sperm and ova before fertilisation can occur. Strong currents carry sperm cells away before fertilisation can occur. Reproduction must take place in water otherwise gametes or fertilised ova will dehydrate.

6. INTERNAL FERTILISATION: ADVANTAGES & DISADVANTAGES Ensures that the sperm cell come into contact with the ovum Developing embryo is protected from predators and removed from harsh environment Fewer eggs are produced The animal must have a copulatory organ to insert sperm cells into the female body

7. EXTERNAL FERTILISATION VS INTERNAL FERTILISATION

8. OVIPARY, OVOVIVIPARY AND OVIPARY OVIPARY Ovi / pary Egg + bearing Eggs are laid, and development of the embryo occurs outside the female’s body. OVOVIVIPARY Ovo / vivi / pary Egg + live + bearing Eggs develop and hatch within the female’s body and young are born live. VIVIPARY Vivi / pary Live + bearing No eggs are present, young develop from the placenta and are born live Important definitions

9. COMPARISON OF OVIPARY, OVOVIVIPARY AND VIVIPARY

10. EMBRYONIC DEVELOPMENT: Ovipary and Ovovivipary EMBRYONIC DEVELOPMENT Advantages: Eggs and sperm cells are produced in large numbers to increase chances of survival to adulthood. Parental care ensures survival to adulthood. (Precocial) Advantages: The young one is protected from cold and predators to ensure survival. The young are well developed when born therefore their chances of survival increases because they will be able to evade their predators.

11. EMBRYONIC DEVELOPMENT: Vivipary Advantages: Development occurs within the mother’s body ensuring protection of the developing young. The young are born well developed and are therefore less prone to being attacked. Parental care increases the chances of survival of the young. Disadvantages: Number of off springs produced is few . More energy is used to provide parental care.

12. AMNIOTIC EGG The embryo develops inside the amnion and is protected by many membranes and a hard shell . Amniotic fluid protects the embryo from drying out . It feeds from the yolk . The allantois removes metabolic wastes. The chorion supplies oxygen, food and water.

13. PRECOCIAL & ALTRICIAL DEVELOPMENT PRECOCIAL When they hatch their eyes are open . Their bodies are covered with soft feathers . They are able to move soon after they have hatched. They are able to feed themselves . They are independent of their parents. - ALTRICIAL Young are highly developed and able to move about and feed themselves Young ones are unable to move after birth and are helpless. They do not have feathers (birds) and blind. They need to be fed and kept warm. Immature and need a lot of parental care

14. PARENTAL CARE Refers to looking after young ones through feeding, keeping them warm, protecting them from the predators. Such animals give rise to few offspring.

15. MTG summary p17

16. MTG summary continues

17. Question 1 1. Name the type of fertilisation that takes place in the bottlenose dolphin. (1) Internal fertilisation  Explain how TWO of the reproductive strategies of the great white shark increase its reproductive success. (4) Internal fertilisation  increases the chances of fertilisation  Ovovivipary  / eggs retained inside the female’s body for better protection from predators/harsh environment  The bluefin tuna, the great white shark and the bottlenose dolphin are three aquatic species that are found in the Indian Ocean. An adult bluefin releases up to 540 000 000 eggs into the water annually, while the great white shark female produces 2 to 12 offspring through ovovivipary every two years. A bottlenose dolphin female, being a mammal, is viviparous and produces one offspring every two to three years. Explain ONE reason why the bluefin tuna releases a large number of eggs. (2) To increase the chances of fertilisation  since there is external fertilisation  OR To increase the survival of the eggs  /number of offspring As eggs may be lost to predators  /environmental factors

18. Question 2 (Gauteng Prelim P1 2022) The diagrams below show the internal structure of an amniotic egg after fertilisation, as well as the chick that hatched from the egg. 2.1 Name the type of fertilization that has taken place. (1) Internal  fertilisation 2.2 State the type of reproductive strategy which is shown by the development of an embryo within an amniotic egg. (1) Ovipary  2.3 Identify the type of development that the hatched chick shows. (1) Altricial  2.4 Give TWO functions of the amniotic fluid. (2) Protects the foetus against shock  /mechanical injuries Keeps the foetus moist  /Protects the foetus from drying out Protects the foetus from temperature changes  Allows the foetus to move freely  /Supports the body of the foetus during development

19. Question 2 (Gauteng Prelim P1 2022) The diagrams below show the internal structure of an amniotic egg after fertilisation, as well as the chick that hatched from the egg. 2.5 Explain how the size of the yolk sac affects the development of the chick in the diagram. (3) The yolk sac was smaller  Therefore, (the chick) it received less nutrients  in the form of yolk - (The chick) it is less developed  /underdeveloped/eyes are closed/has only down feathers/has no feathers/cannot walk/shows altricial development

20. Question 3 (DBE Nov P1 2022) 3.1 Name the type of fertilisation that takes place in both fish species. (1) External  fertilisation 3.2 Explain why both fish species are oviparous. (2) - Their embryos develop inside eggs  - Which are laid/hatch outside the body of the female  3.3 Describe TWO ways in which the chances of fertilisation are increased in the northern pike fish.(2) - The males release semen all around the female when she releases the eggs  - A large number of gametes/eggs are produced 

21. Question 3 (DBE Nov P1 2022) 3.4 Which graph ( X or Y ) represents the survival rate of the northern pike fish? (1) Graph X  3.5 Explain your answer to QUESTION 3.4. (3) They will have a higher number of surviving embryos  /eggs Because their fertilised eggs are attached to the vegetation  Where they are protected from predators  /washing away

22. Question 4 (KZN Prelim P1 2023) 4.1 State whether crocodiles have internal or external fertilisation. (1) Internal  fertilisation 4.2 Explain TWO ways in which the type of fertilisation, named in QUESTION 4.1, increases reproductive success in crocodiles. (4) Sperms are deposited inside the female body  Which increases the chances of fertilisation  Protection provided by the mother’s body decreases  mortality rate  4.3 Name the type of reproductive strategy in crocodiles which relates to the nourishment and protection of the developing embryo. (1) Ovipary 

23. Question 4 (KZN Prelim P1 2023) 4.4 Name TWO ways, mentioned in the passage, which indicates that crocodiles have parental care. (2) Removes the debris from the egg  Assists the hatchling to the water  Opens the eggs carefully with her tongue  Carries the hatchlings in her mouth 

24. END OF THE PRESENTATION