Lessons 1–3 · 3 lessons · O. Pratov, A. Tukhtaev, F. Azimova, I. Saparboev, M. Umaraliyeva. Biology (Botany), Grade 6. O‘zbekiston Publishing House, Tashkent, 2017
2
General introduction to flowering plants
Textbook: p. 7
GoalTell apart the organs of flowering plants (vegetative and generative) and explain their diversity.
Flowering plants are the most varied group of the plant world, with hundreds of thousands of species (the textbook says over 250,000). Their body consists of root, stem, leaf, flower, fruit and seed. Root, stem and leaf provide growth and nutrition, so they are called vegetative organs (Latin “vegetatio” — growth). Flower, fruit and seed provide reproduction and are called generative organs (Latin “generare” — to create). Conditions have changed over millions of years; plants adapted to new surroundings, useful features were passed on (inherited) and fixed, and those that could not adapt died out. That is why saksovul (saxaul) can grow in hot sand, nilufar (water lily) in water and archa (juniper) in the mountains.
The environment changes→The plant adapts to the new environment→Useful traits are inherited and fixed
Worked examples
The water lily’s stem is under water and its flower opens on the surface — adaptation to life in water. Saksovul (saxaul) has tiny leaves and loses little water — adaptation to the hot desert.
The flower of Rafflesia on Sumatra can reach 1 m across — one of the largest flowers in the world. The nut of the Seychelles palm can weigh up to 25 kg.
Class activity
“Organ–job” game: the teacher says an organ (root, flower, leaf, fruit…); pupils answer “vegetative” or “generative” and say its job in one sentence.
Practice
1
Which organs of a flowering plant are vegetative and which are generative?