Hormonal Influences

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Anonymous
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146746
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Hormonal Influences
Updated:
2012-04-10 10:03:42
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Hormonal Influences Biology
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Higher Biology - Unit Three - Hormonal Influences
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  1. What are hormones?
    Hormones are the chemical messengers (proteins) that send signals from one part of the body to another
  2. Where are hormones secreted into in humans?
    The bloodstream
  3. What part of the brain produces many hormones?
    The pituitary gland
  4. How does human growth hormone stimulate growth?
    • It Increases uptake of amino acids into soft tissue and bone cells
    • Promotes synthesis of tissue proteins eg long bones during growing years
  5. What happens as a result of under-production of human growth hormone during adolescence?
    Reduction in overall growth = pituitary dwarfism
  6. What happens as a result of over-production of human growth hormone during adolescence?
    Increase in overall growth, especially long bones = gigantism
  7. What happens as a result of over-production of human growth hormone during adulthood?
    Enlargement of hand, foot and jaw bones = acromegaly
  8. _____ is produced by the pituitary gland and controls the growth and activity of the thyroid gland?
    TSH - thyroid stimulating hormone
  9. TSH induces the formation of ________ in the thyroid gland which controls the body's metabolic rate and growth?
    thyroxine
  10. What happens as a result of over-production of TSH? (all ages)
    Too much thyroxine produced = increased size and activity of thyroid gland and swollen neck and bulging eyes
  11. What happens as a result of under-production of TSH as a child?
    Too little thyroxine produced = decreased mental and skeletal development
  12. What happens as a result of under-production of TSH as an adult?
    Too little thyroxine produced = lethargy and increased weight
  13. What is the most common type of auxin?
    Indole acetic acid - IAA
  14. What is IAA produced by?
    The root and shoot tips and leaf meristems
  15. What does IAA do?
    • Stimulates cell division in apical meristems and cambium
    • Promotes cell elongation in apical and lateral meristems
    • Is necessary for cell differentiation
  16. What is the result of low levels of IAA in a plant?
    • Stimulates root growth
    • Does not effect shoot growth
  17. What is the result of high levels of IAA in a plant?
    • Stimulates shoot growth
    • Inhibits root growth
  18. What is the result of very high levels of IAA in a plant?
    Inhibits shoot and root growth
  19. What is phototropism?
    The directional growth of a plant in response to light from one direction
  20. A unidirectional light source causes an equal / unequal distribution of hormone in the tip
    unequal
  21. There is a higher concentration of auxin in the illuminated / non-illuminated side?
    non-illuminated
  22. When the shoot bends towards the light this is called...?
    positive phototropism
  23. High levels of auxin produced by the apical buds prevent the growth of _____ buds?
    lateral
  24. Seperation of a leaf from a plant is called ...?
    abscission
  25. Give one commercial use of auxins
    • Produce seedless fruits
    • Delay abscission of fruits to prevent fruit dropping before they are ripe
    • Induce root growth in shoot cuttings - rooting powder
    • Selective herbicide on grass where it kills broad-leaved plants eg dandelion but not the grass
  26. What is the most common gibberellin?
    Gibberellic acid - GA
  27. What do gibberellins do?
    • Stimulate cell division and elongation in stems
    • Break dormancy in buds and seeds
    • Cause an increase in length of internodes (the space between two sets of leaves)

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