15.2.114-15 · Homeostasis and Control
Electrical Communication in the Venus Flytrap — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions
5 min read 8 parts Lesson 28 of 31 Unit quiz
Lesson summary
15.2.1 Electrical Communication in the Venus Flytrap — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Explain how touch on sensory hairs causes the Venus flytrap to close and digest prey.Plant — a carnivorous plant that gains nitrogen compounds from small animals, ma…
- Efficiency
- Single touch
- Hinge cell
- Receptor potential
- Exocytosis
- Elongation
Section 1 of 8Structure of the trap
Structure of the trap
Plant
- Plant a carnivorous plant that gains nitrogen compounds from small animals, mainly insects.
Leaf
- Leaf divided into two lobes on either side of a midrib.
Inside
- Inside red, with nectar-secreting glands on the edges that attract insects.
Sensory hairs
- Sensory hairs three stiff hairs on each lobe that detect touch.
Section 2 of 8Response to touch
Stimulus
- Stimulus an insect touching a hair generates action potentials.
Result
- Result the two lobes fold together along the midrib, capturing the insect.
Section 3 of 8Closing the trap
1
An insect lands on the leaf and touches the sensory hairs.
2
Calcium ion channels in hinge cells at the base of the hair open.
3
Ca2+ flow into the hinge cells and generate a receptor potential.
4
If two hairs are stimulated at the same time, or one hair twice within about 30 seconds, an action potential is propagated across the trap cells.
5
The hinge cells at the base of the trap expand as water moves in, and the trap closes.
Section 4 of 8Why two stimuli are needed
Efficiency
- Efficiency the plant does not waste energy closing when no insect is present.
Single touch
- Single touch a single stimulus does not close the trap.
Section 5 of 8Sealing and digestion
1
Prey moving inside keeps stimulating the sensory hairs, which seals the trap.
2
Further stimulation lets Ca2+ enter gland cells.
3
Ca2+ stimulate exocytosis of vesicles containing digestive enzymes.
4
The trap stays closed for up to a week while nutrients are digested and absorbed.
Section 6 of 8More from the specification
Action potentials contrasting with plant auxins
- Action potentials contrasting with plant auxins rapid electrical trap closure involves ATP-driven proton pumps, contrasting with slow cell elongation mediated by auxins.
Cytoplasm
- The jelly in which the cell's chemical reactions happen.
Aleurone layer
- Protein-rich layer around the endosperm.
Growth
- A permanent increase in size and dry mass.
Elongation
- Increase in cell length.
Gibberellin
- Hormone stimulating germination and stem elongation.
Germination
- The start of growth of a seed.
Embryo
- A little ball of cells that forms from the first cell and develops into a baby.
Amylase
- Enzyme that breaks starch into maltose.
Endosperm
- Triploid food tissue in the seed that feeds the embryo
Auxin
- A plant hormone made in shoot and root tips that controls cell elongation.
Section 7 of 8Key terms
| Term | Meaning |
|---|---|
| Venus flytrap | Carnivorous plant with snap-closing leaf lobes. |
| Sensory hair | Touch-detecting hair on the trap lobe. |
| Hinge cell | Cell at the base of the trap that expands to close it. |
| Receptor potential | Depolarisation produced when Ca2+ enters. |
| Exocytosis | Release of vesicle contents from a cell. |
| Midrib | Central rib of the leaf between the two lobes. |
Section 8 of 8Exam technique
1
Saying the trap closes on a single touch — two stimulations are needed.
2
Saying the plant has neurones — it uses electrical signals through cells.
3
Saying digestive enzymes are released before sealing — release follows ongoing stimulation.
4
Forgetting hinge cells — they expand to close the trap.
Last updated: