homeostasis🧜♀️🧚♀️🧚 Flashcards
1
Q
how do large thin ears help elephants control body temp
A
- large surface area
- blood vessels close to skin surface
- flapping increases air movement over skin
2
Q
what is homeostasis
A
- maintaining stable internal environment -within narrow ranges
- eventhough environment is changing
3
Q
describe how negative feedback is used to control blood glucose
A
- receptors detect change in blood glucose
- beta cells secrete insulin
- insulin causes glycogenesis
- increased uptake of glucose by liver cells
- alpha cells secrete glucagon
- glucagon causes glycogenolysis
4
Q
what is an endotherm
A
uses internal sources of heat to maintain body temp
5
Q
what is ectotherm
A
-depend on external heat sources
6
Q
compare ecto and endotherm
A
- ecto need less food than endo
- ecto can survive longer periods with no food than endo
- ecto use greater proportion of energy on growth
- endo can inhabit colder habitats than ecto
- endo body temp is more constant than ecto
- endo is able to be active even when cold so less risk of predation than ecto
7
Q
give an example of positive feedback
A
- giving birth
- head of baby pushes against cervix
- nerve impulses from cervix to brain
- brain stimulates pituitary gland to secrete oxytocin
- oxytocin carried to uterus in blood
- oxytocin stimulates uterine contractions and pushes baby towards cervix
8
Q
how does weed killer work
A
- very high concentration of auxin
- rapid growth distorts/damages plant so pathogens may enter
- effective against weeds in fields of cereal or grass as they are less sensitive to the killers so remain
9
Q
how does rooting powder work
A
-at low doses auxin can stimulate cuttings to grow new roots
-low end of cutting dipped in powder then put in compost
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10
Q
how can fruit ripening be controlled
A
- fruits harvested when unripe
- artificially ripened in transport or later
11
Q
how are seedless fruits made
A
-auxins and gibberellins used to make unpollinated flowers develop fruit
-these fruits form without fertilisation
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