Support in plants — KCSE Biology

KCSE Biology · 97 practice questions · 2 syllabus objectives · 2 revision lessons

37 easy37 medium23 hard

Last updated · Aligned to the KNEC KCSE syllabus

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

State the functions of turgor pressure and lignification in plant support

Support in plants

Revision Notes

Concise lesson notes for Support in plants, written to the KCSE Biology marking standard. Read the first lesson free below.

Functions of Turgor Pressure and Lignification

Turgor pressure and lignification are crucial for maintaining support in plants. Turgor pressure is the pressure of the cell contents against the cell wall, which is vital for:

  • Maintaining cell shape: It keeps plant cells rigid and prevents wilting.
  • Facilitating growth: Turgor pressure helps in cell expansion during growth phases.
  • Transport of nutrients: It aids in the movement of water and nutrients through plant tissues.

Lignification refers to the process of deposition of lignin, a complex organic polymer, in cell walls, which enhances:

  • Structural strength: Lignin provides rigidity and strength to woody plants, allowing them to grow tall.
  • Resistance to decay: Lignified cells are more resistant to pathogens and environmental factors.
  • Water conduction: Lignin helps in the formation of xylem vessels, essential for water transport.

Understanding these functions is vital as they illustrate how plants maintain their structure and adapt to their environments.

Key points to remember

  • Turgor pressure maintains cell shape and prevents wilting.
  • It facilitates growth by aiding cell expansion.
  • Lignification provides structural strength to plants.
  • Lignin enhances resistance to decay and pathogens.
  • Lignified cells are crucial for efficient water conduction.

Worked example

State two functions of turgor pressure in plants.

  • Turgor pressure maintains cell shape and prevents wilting.
  • It facilitates the transport of nutrients and water.

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More lessons in this topic

Lesson 2: Understanding Support in Plants

Objective: Support in plants

Plants require support to maintain their structure and stability. Support in plants is primarily provided by:

  • Cellulose: This is a key component of the plant cell wall, giving rigidity and strength.
  • Turgor Pressure: The pressure of the cell contents against the cell wall helps keep the plant upright.
  • Lignin: A complex organic polymer found in secondary cell walls, particularly in woody plants, which adds strength.
  • Root Systems: Deep and extensive roots anchor the plant to the soil, providing stability against wind and water.

Different types of plants display various support mechanisms. For example:

  • Herbaceous plants rely more on turgor pressure for support.
  • Woody plants utilize lignin and a robust root system to withstand environmental stresses.

In summary, support in plants is vital for growth, photosynthesis, and overall health. Without adequate support, plants may collapse or fail to thrive.

  • Cellulose provides rigidity to plant cell walls.
  • Turgor pressure maintains plant uprightness.
  • Lignin adds strength in woody plants.
  • Root systems anchor plants in the soil.
  • Support is essential for healthy plant growth.

Explain how turgor pressure contributes to support in plants.

  • Turgor pressure is the pressure of the cell contents against the cell wall.
  • It helps maintain the plant's upright position and prevents wilting.

Sample Questions

Read 3 questions and answers free. Sign up to access all 97 questions with full KNEC-style marking schemes and a personalised study plan.

1
easySHORT ANSWER1 mark

Name the material that strengthens xylem tissue in plants.

Answer & marking scheme

Part (a) — 1 mark
Lignin (1 mk)
2
easySHORT ANSWER3 marks

In the study of plant biology, understanding the mechanisms that provide structural integrity and resilience is crucial. This includes examining the roles of various tissues and the impact of environmental conditions on plant support. (a) State two ways in which non-woody plants are supported. (2 marks) (b) Name the tissues responsible for support in plants. (2 marks) (c) Explain why herbaceous plants wilt when they are dehydrated. (2 marks)

Answer & marking scheme

Part (a) — 3 marks
Any 2 valid support mechanisms — 1 mark each (1 mk)
3
easySHORT ANSWER6 marks

Plants exhibit various mechanisms to maintain structural integrity and withstand environmental challenges. Understanding the different forms of support and the role of specific tissues is essential in appreciating how these organisms thrive in diverse habitats. (a) State two ways in which plants are supported. (2 marks) (b) Name the tissues responsible for support in plants. (2 marks) (c) Explain why herbaceous plants wilt when they lose water. (2 marks)

Answer & marking scheme

Part (a) — 2 marks
Turgor pressure in cells provides support in herbaceous plants (1 mk)
Lignified tissues (xylem, sclerenchyma) provide mechanical support in woody plants (1 mk)
Part (b) — 2 marks
Xylem vessels / sclerenchyma fibres / collenchyma (2 mks)
Part (c) — 2 marks
Loss of water reduces turgor pressure in cells; cells become flaccid (1 mk)
Without turgor pressure, the stem cannot remain upright and the plant droops/wilts (1 mk)
4

In the study of plant physiology, understanding the mechanisms that contribute to structural integrity and resilience is essential. This includes examining the effects of water availability and the physiological responses of plants under stress conditions. (a) Define the term wilting. (1 mark) (b) State one importance of wilting to a plant. (1 mark) (c) Explain what happens when a wilting young plant is well watered. (3 marks)

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Frequently asked questions

What does the KCSE Biology topic "Support in plants" cover?

Support in plants covers State the functions of turgor pressure and lignification in plant support; Support in plants, all aligned to the official KNEC KCSE Biology syllabus.

How many practice questions are available for Support in plants?

HighMarks has 97 Support in plants practice questions for KCSE Biology, each with a full marking scheme. The first 3 are free; sign up to access the rest, plus all KCSE mock exams and past papers.

Are these aligned with the KNEC KCSE syllabus?

Yes. Every objective on this page is taken directly from the official KNEC KCSE Biology syllabus. Practice questions match the KCSE exam format and are graded against the standard KNEC marking scheme.

How should I revise Support in plants for the KCSE exam?

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