Coordination In Plants And Mammals Flashcards
How are the nervous and hormonal system linked in the brain?
The hypothalamus is a small part of the brain that links the nervous and endocrine systems.
It controls hormone secretion via the pituitary gland located below it.
The hormones secreted by the pituitary gland controls hormone secretion by other endocrine glands
State three differences between nervous and hormonal coordination
– Nervous coordination is faster than hormonal coordination
– Nervous coordination is more short-lived than hormonal
coordination
– Nervous coordination involves electrical information moving
along neurones, whereas hormonal coordination involves
chemical information moving via the circulatory system
Name a hormone synthesised by neurosecretory cells in the hypothalamus
ADH or oxytocin
Name a plant growth substance that stimulates cell growth
Auxin
Name a plant growth substance that inhibits germination in seeds
Abscisic acid
Name a plant growth substance that promotes the growth of lateral buds and leaves in stems
Cytokinin
Name a plant growth substance that inhibits root growth at high concentration
Auxin
List the ways in which abscisic acid influences physiological processes in plants
Stimulates the closing of stomata when water is in short supply
May play a part in leaf fall in some deciduous trees
Inhibits germination in seeds
List the ways in which cytokinins influence physiological processes in plants
Stimulate cell division
Promote the growth of lateral buds and leaves in stems
Delay senescence (ageing) in leaves
Name a plant growth substance that stimulates the ripening of fruit
Ethene
Name a plant growth substance that stimulates germination
Gibberellin
Distinguish between synergistic and antagonistic interaction among plant growth substances
When plant growth substances act synergistically, their combined action produces a greater than would be expected from adding the individual effects of each substance
When they antagonistically, their combined action produces a smaller effect than would be expected from adding the individual effects of each substance
State four commercial uses for plant growth substances, identifying the substances involved in each case
Promoting the rooting of cuttings – auxins
Selective killing of weeds – auxins
Inducing fruit ripening – ethene
Producing seedless fruit – gibberellins
What are photoreceptors?
Cells that are sensitive to light
Explain the importance of light in phototropism
Phototropism is a change in growth response to light
Most stems are positively phototropic, because they grow towards light
Roots are negatively phototropic, growing away from light
