UNIT 4

1. UNIT4 The reproduction function ALTERNATION OF GENERATIONS IN A FERN Natural Science 2. Secondary Education

2. UNIT4 Alternation of generations in a fern The different stages of the process Click on each picture to find out more 3 Young sporophyte 4 Zygote Sexual organs ofthe gametophyte Femalegamete Female sexual organ Male sexual organ 2 Sporangium Male gametes Sporophyte 1 Gametophyte Natural Science 2. Secondary Education

3. UNIT4 Alternation of generations in a fern Sporophyte • This is the part of the fern that we can see. • On the underside of its leaves, called fronds, are the sporangia. Frond Sporophyte Sporangium Go back to the Start menu Natural Science 2. Secondary Education

4. UNIT4 Alternation of generations in a fern Sporangia • This is where spores are formed and mature. • Gametophytes come from spores. Sporangium Spores Go back to the Start menu Natural Science 2. Secondary Education

5. UNIT4 Alternation of generations in a fern Gametophytes • They develop from spores. • They are very small. • They have sexual organs, which produce male and female gametes. Female gamete Gametophyte Female sexual organ Male gametes, which need water in order to reach the female organ. Male sexual organ Go back to the Start menu Natural Science 2. Secondary Education

6. UNIT4 Alternation of generations in a fern Zygote • The union of a male gamete and a female gamete produces the zygote. • The development of the zygote produces a new sporophyte. Zygote Sporophyte Young sporophyte Go back to the Start menu Natural Science 2. Secondary Education