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Biology > Biology- Unit 9 > Flashcards

Biology- Unit 9 Flashcards

1
Q

Where are hormones secreted from?

A

Endocrine glands

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2
Q

What are the two modes of hormone action?

A

1) Bind to a receptor on the target cell membrane which stimulates the release of a second messenger which activates enzymes
2) Pass through the cell membrane and bind to a receptor inside cell, forms hormone-receptor complex which passes into nucleus and acts as transcription factor

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3
Q

What are the functions of auxins?

A

Growth stimulant
Maintain apical dominance
Promote root growth
Promote trophic responses (directional growth)
Can be used as weed killer and rooting powder

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4
Q

What do auxins do to achieve this?

A

Cause cell elongation via AT of H+ into cell walls = more acidic
More acidic = more flexible = more stretch to accommodate more water

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5
Q

What are the functions of gibberellins?

A

Stimulate elongation at cell internodes
Stimulate growth of fruit
Stimulate germination
Stimulate rapid growth / flowering

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6
Q

How does gibberellins stimulate germination?

A 
Seed absorbs water, activates embryo
Embryo secretes gibberellins
G diffuses into aleurone layer
Aleurone layer produces amylase
Amylase diffuses into endosperm and breaks down starch into glucose
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7
Q

What are the functions of cytokinis

A

Promote cell division / lateral bud development

Works with ethane to promote abscission of leaves

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8
Q

What are the two forms of phytochrome

A 
Pr = inactive, absorbs red light (sun)
Pfr = active, absorbs far red light
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9
Q

In long-day plants, Pfr…?

A

Stimulates flowering

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10
Q

In short-day plants, Pfr…?

A

Inhibits flowering

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11
Q

What does a plant look like when kept in the dark

A 
Only has Pr
Tall and thin
Fragile stems
Yellowed leaves
Little root growth
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12
Q

What systems form the peripheral nervous system?

A

Autonomic (non-conscious)
Sympathetic (fight/flight)
Parasympathetic (rest/digest)
Voluntary (conscious)

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13
Q

What is the neurotransmitter for the sympathetic system?

A

Noradrenaline

Ganglia close to CNS

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14
Q

What is the neurotransmitter for the parasympathetic system?

A

Acetylcholine

Ganglia far from CNS

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15
Q

What is the function of the hypothalamus?

A

Thermoregulation
Osmoregulation
Hormone secretions

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16
Q

What is the function of the cerebellum?

A

Smooth movements
Balance
Posture

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17
Q

What is the function of the cerebrum?

A

Voluntary behaviour

Personality

18
Q

What is the function of the medulla oblongata?

A

Breathing
Heart rate
Peristalsis

19
Q

What is the function of motor neurones?

A

Transmitting potential differences from CNS to muscles and glands

20
Q

What is the function of sensory neurones?

A

Transmit impulses from receptor cells to CNS

21
Q

What is the function of relay neurones?

A

Located within CNS

Transmit impulses from sensory to motor

22
Q

What is the resting potential value?

A

-70mV

23
Q

What is the function of the myelin sheath?

A

Insulator of axon and dendron

Salutatory conduction

24
Q

What is the effect of nicotine on the nervous system?

A

Mimics acetylcholine
Triggers release of dopamine
In high doses, blocks acetylcholine receptors

25
Q

What is the effect of cobra venom on the nervous system?

A

Binds to and blocks acetylcholine receptors

26
Q

What pigment do rods contain?

A

Rhodopsin

Splits into retinal and opsin

27
Q

What happens to rods in the dark?

A

Rods aren’t stimulated- sodium ions diffuse into the cell through channels whilst being pumped out via AT
The inside of the cell is only slightly more negative
Membrane slightly depolarised
Glutamate released- inhibit rod neurones
No info goes to brain

28
Q

What happens to rods in the light?

A

Rhodopsin splits into retinal and opsin - bleaching
Opsin binds to membrane of cells closing the Na+ channels
Cell membrane becomes hyperpolarised
Action potential forms and is transmitted to brain

29
Q

What factors increase heart rate?

A

Low pH
Stretch receptors
Decrease in BP
Adrenaline

30
Q

How is a low blood pH detected?

A

Chemoreceptors in arteries, aorta and brain

Send impulses to medulla oblongata

31
Q

How does heart rate increase?

A

Receptor sends impulse to cardiac control centre in medulla oblongata
Impulse sent to SAN along sympathetic neurone
Depolarisation occurs
Noradrenaline released at SAN

32
Q

How does heart rate decrease?

A

Receptor sends impulse to cardiac control centre in medulla oblongata
Impulse sent to SAN via parasympathetic neurone
Depolarisation occurs
Acetylcholine released at SAN

33
Q

What is deamination?

A

Liver- hepatocytes
Amino acids converted into urea
Amine group is removed to form ammonia
Ammonia converted into urea- Orithine cycle

34
Q

Why is ammonia converted into urea?

A

Ammonia is extremely toxic

35
Q

Describe ultrafiltration

A

Occurs in glomerulus and bowman’s capsule
Small molecules forced out of vessel under high pressure
Afferent arteriole (entering) is wider than efferent arteriole (leaving)

36
Q

Where does selective reabsorption occur?

A

Proximal convoluted tubule
All glucose and amino acids reabsorbed by FD and AT
Water diffuses via osmosis

37
Q

What occurs in the loop of henle?

A

Medulla extremely low water potential
Descending limb- permeable to H2O
Ascending limb- not permeable to H2O
Water moves through aquaporins via osmosis into low WP in medulla
Ascending limb-
Ions move via FD into medulla to maintain WP in descending
Upper ascending = AT of ions

38
Q

What occurs in the distal convoluted tubule?

A

Secretes waste like creatine into filtrate
Actively transports ions
Helps control blood volume
Regulates pH

39
Q

What occurs in the collecting duct?

A

ADH
Osmoreceptors in hypothalamus detect water potential
More ADH = more permeable = more reabsorption

40
Q

What is an ecotherm?

A

Organism that cannot regulate its body temperature

41
Q

What is an endotherm?

A

Able to maintain a constant body temp
Contain thermoreceptors
Hypothalamus
Restore optimum temp

42
Q

What can endotherms do to regulate heat?

A

Shivering - increases
Sweat glands - decreases
Hairs - increases
Arterioles - vasodilation/ constriction

Biology (10 decks)

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