9.3 Growth in plants

Essential idea: Plants adapt their growth to environmental conditions.

Boxwood, Pivet and Yew are plants commonly used for topiary. Topiary involves both encouraging growth in specific directions by use of frameworks and pruning, amongst other techniques. Though human in origin topiary can be considered a change in the environment that causes a change in growth.

Understandings, Applications and Skills

9.3.U1	Undifferentiated cells in the meristems of plants allow indeterminate growth.
9.3.U2	Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves.
9.3.U3	Plant hormones control growth in the shoot apex. [Auxin is the only named hormone that is expected.]
9.3.U4	Plant shoots respond to the environment by tropisms.
9.3.U5	Auxin efflux pumps can set up concentration gradients of auxin in plant tissue.
9.3.U6	Auxin influences cell growth rates by changing the pattern of gene expression.
9.3.A1	Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones.
9.3.A2	Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species.

[Text in square brackets indicates guidance notes]

Presentation and Notes

The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.

Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.

Use the Cornell style template to collate your own notes for Topic 9 - Plant biology

Labs/investigation ideas

Micropropagation (by SAPS) is a fun easy to setup lab that can be done at the start of the topic. Students can then monitor the results over a period of weeks.

Quick quiz

Use the BioK Quick Quiz on 9.3 Growth in plants (as directed) to check your understanding of the topic.

Nature of science

Developments in scientific research follow improvements in analysis and deduction—improvements in analytical techniques allowing the detection of trace amounts of substances has led to advances in the understanding of plant hormones and their effect on gene expression. (1.8)

Theory of knowledge:

Plants communicate chemically both internally and externally. To what extent can plants be said to have language?

There are many articles on this subject. Click on the cartoon to read one such article from the Daily Mail.