Multicellular Organisms

Watch the video... and answer the questions.

Multicellular Organisms Multicellular organisms are organisms made up of many different cells.

Reproduction Relay! How many words related to reproduction can you remember?

Reproduction Reproduction is the production of new members of a species. If organisms fail to reproduce the species could become extinct. This can happen sexually or asexually.

Reproduction To reproduce sexually, sex cells (gametes) are required. Draw a labelled diagram of a sperm cell and an egg cell in your jotter.

Gametes

Fertilisation In order for reproduction to be successful, fertilisation must take place. Fertilisation occurs when the nucleus of the sperm fuses with the nucleus of an egg cell to produce a zygote. A zygote is the first cell formed immediately after fertilisation.

Reproductive Systems You have been given diagrams of the male and female reproductive systems. Label these as much as you can using your knowledge from S1/2.

Question time! Name the two main ways in which reproduction can take place. Give another name for sex cells. State one similarity and one difference between an egg cell and a sperm cell. Describe what happens during fertilisation. Name the cell which is formed as a result of fertilisation.

Reproduction Recap

Reproduction Recap

Watch the video clip... What are the main steps in the process of fertilisation?

Fertilisation Using the sheet provided try to complete the diagram by labelling the steps correctly.

Internal Fertilisation Internal fertilisation occurs when the sperm and egg meet inside the female’s body. It is essential the fertilisation in land animals takes place internally since there is no water outside to carry the sperm to the egg.

The Developing Embryo After fertilisation the zygote begins to move along the oviduct and divide by doubling. It then implants in the side of the womb.

The Developing Embryo As the embryo develops it relies on the placenta. Use your knowledge from S1/2 to complete the sheet about the function of the placenta.

One thing you have learned today...

External Fertilisation External fertilisation occurs when the sperm and egg meet in the water surrounding the parents. This occurs commonly in fish.

Internal vs External Fertilisation Use the table provided to compare internal and external fertilisation.

Internal vs External Fertilisation Internal Fertilisation External Fertilisation Examples of organisms Fertilisation takes place inside or outside of the mother’s body Inside mothers body Outside the mothers body Fertilised eggs released in to water or stay inside the mother Sperm sprayed on to the eggs or sperm placed inside mother Few or very many eggs produced Young develop inside or outside mother’s body Most or some of the eggs get fertilised Most or few of the offspring (babies) survive Eggs or offspring (babies) looked after, or not looked after by parents Parents build a nest or no nest

Problem solving skills.

The Developing Embryo Plot a graph to demonstrate the development of the zygote into an embryo. Time (mins) Number of Cells 1 30 2 60 4 90 8 120 16 150 32 180 64

Problem Solving Stations Work your way around the stations practicing your problem solving skills. You have 10 mins at each station.

Sexual Reproduction in Plants

Watch the video clip... What are the main structures found in a flower?

Task Your task is to dissect the flower and label the different structures accurately. Match the structures to their functions using the sheet provided.

Asexual Reproduction Does not involve sex cells or fertilisation. Only involves one parent. The offspring are genetically identical to the parent

Asexual Reproduction - Examples Bacteria are one example of asexual reproduction

Asexual Reproduction - Examples Tubers (potato), bulbs (garlic) and runner (strawberry) plants are other examples of asexual reproduction

Asexual Reproduction - Examples Starfish and sea anemones are other examples of asexual reproduction

Sexual vs Asexual Sexual Asexual