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Biology Semester Two > Plant Tropisms And Hormones > Flashcards

Plant Tropisms And Hormones Flashcards

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0
Q

Animals responding to changes in environmental conditions

A

Are able to move to where conditions are more favourable and nutrients are available.
A stable internal environment is maintained in the face of change external conditions.
Nervous and hormonal systems promote internal stability.

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1
Q

Plants responding to changes in environmental conditions

A

Must stay where the seed germinates.
Must get their requirements from their immediate environment.
Plant growth and reproduction is aligned with the seasons.
Plants have no nervous system, hormone carry the messages.

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2
Q

What is a hormone?

A

A chemical produced by cells in one part of an organism and transported through the organism to where it acts.

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3
Q

Hormones….

A

Act as intercellular messengers.
In animals will only affect a specific target group cells.
Hormonal effects are slower than nervous responses.

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4
Q

Hormones in plants are responsible for….

A

Phototropism
Geotropism
Apical dominance- inhibition of lateral (side) branches
Growth of the entire plant- germination, fruits, flowers
Ripening of fruit- conversion of starches to sugars
Abscission- shedding of leaves and flowers

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5
Q

Plants respond to the environment in the following ways…

A

Sensing light
Sensing gravity
Sensing touch

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6
Q

Sensing light

A

Phototropism, where a shoot grows towards light, is a response to blue light. The pigment carotene is likely to be included.

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7
Q

Sensing gravity

A

Geotropism, shoots are negatively geotropic: they grow away from the pull of gravity and therefore upwards, out of the soil. In contrast, roots are positively geotropic: they grow towards the pull of gravity.

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8
Q

Sensing touch

A

Thigmotropism refers to growth responses that occur as a result of contact with a surface. The cooling and bending of tendrils around objects, as in pea plants and vines, is the result of thigmotropism.

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9
Q

Define: phototropism

A

Change in the direction of plant growth in response to light.

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10
Q

Define: geotropism

A

The growth of roots in response to the pull of gravity.

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11
Q

What are auxins?

A

Auxins are plant hormones that promote growth of new shoots, trigger positive phototropism and negative geotropism of shoots and are responsible for apical dominance.

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12
Q

What is apical dominance?

A

Where the main central stem of a plant is dominant over the other stems.

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13
Q

Gibberellins

A

Promote cell elongation. Growth of the entire plant. Promote cell division, flowering in some plants, fruit enlargement and seed germination.

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14
Q

Cytokinins

A

Are plant hormones that stimulate cell division and differentiation.

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15
Q

Abscisic acid

A

Is a growth-inhibiting hormone that controls a plants response to stress and dormancy.

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16
Q

Ethylene

A

Increases cellular respiration and the processes with fruit ripening.

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17
Q

What is homeostasis?

A

Is the Maintenance of a constant stable internal environment, despite the fluctuations in the external environment, within narrow limits.

That is the tissue fluid around the cells needs to remain in a relatively constant state.

Eg: body temperature in humans is maintained between the temperatures of 36.5-37.5.

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18
Q

What are the advantages of homeostasis?

A

It has survival value because it means an animal can adapt to a changing environment. (Deal with temperature differences)

The body will attempt to maintain a norm. Eg: body temperature at 37 degrees.

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19
Q

What are the disadvantages of homeostasis?

A

It can only work within tolerable limits.
Extreme conditions can disable the negative feedback mechanism.
In these instances, death can result, unless medical treatment is executed to bring about the natural occurrence of these feedback mechanisms.

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20
Q

What is a negative feedback system?

A

A control system where the response produced due to a particular stimulus reduces the size of the original disturbance; which leads to homeostasis.

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21
Q

What does a negative feedback system involve?

A

The nervous or hormonal systems, or both acting together, to promote stability of the internal environment.

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22
Q

The negative feedback process is as follows:

A

The level of glucose in the bloodstream drops (factor decreases).
The person requires glucose in the cells to meet the demand for ATP (corrective response).
The body detects this with a particular receptor designed for this function.
These receptors release hormones (glucagon), chemical messages that initiate the start of the feedback mechanism.
The hormones travel to their target tissue (liver) and initiate a corrective response.

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23
Q

Why is the negative feedback loop essential for survival?

A

It maintains homeostasis within the body.

Constant conditions are required for optimum enzyme function.

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24
Q

Define: stimuli

A

Environmental factors (internal or external) that organisms can detect and to which they respond.

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25
Q

Define: receptors

A

Specialised structure that can detect a specific stimulus and initiate a response.

26
Q

Define: effectors

A

Cells or organs that produce an appropriate response to a particular stimulus.

27
Q

Chemical communication

A

Communication between cells by release of chemicals that interact with specific target cells.

29
Q

Endocrine glands include…and they?

A

Thyroid
Gonads
Anterior pituitary
Typically release hormones directly into the circulatory system which carries them throughout the body.

Salivary glands
Digestive glands
Sweat glands
Typically release their secretions (such as enzymes or salts) via a duct directly to their site of action in the gut to the the exterior of the body.

30
Q

What is the zone of tolerance?

A

The range in which an organism can survive related to a particular abiotic factor.

31
Q

What is a target cell?

A

A cell with the appropriate receptors to respond to a particular chemical signalling molecule.

32
Q

The homeostatic water control is as follows…

A

A change in water concentration occurs (factor increase or decrease).
Osmoreceptors detect water concentration change. These are situated on the hypothalamus next to the circulatory system.
The hypothalamus sends chemical messages to the pituitary gland next to it.
The pituitary gland secrete ADH (anti-diuretic hormone), which targets the kidney responsible for maintains water levels (feedback mechanism).
When the hormone reaches it’s target tissue, it alters the tubules of the kidney to become more/less permeable (corrective response 1)
Or
If less water is required in the blood stream, low concentrations of ADH make tubules less permeable (corrective response 2).

33
Q

Temperature in homeotherms

A

Non dj

34
Q

Corrective mechanisms in temperature control

A

Jhansi

35
Q

Define: thermoregulation

A

Control of body temperature.

36
Q

Define: ectotherm

A

Ecto= outside

An animal that derives body temperature from an external heat source (all animals other than birds and mammals)

37
Q

Define: endotherm

A

Endo= inside

An animal that derives body temperature from internal heat production (birds and mammals)

38
Q

What do ectotherm and endotherm refer/relate to? And what not?

A

The source of body heat. Not whether the animals are capable of regulating body temperature.

39
Q

Define: poikilotherm

A

Poikilo= varied
Body temperature approximates the ambient (related to immediate surroundings) temperature. Not capable of controlling body temperature as ambient temperature varies.

40
Q

Define: heterotherm

A

Hetero= different

Regulates body temperature when active, but allows body temperature to fluctuate with the environment when inactive.

41
Q

Define: homeotherm

A

Controls body temperature, keeping it relatively constant as ambient temperature varies.

42
Q

What do the terms poikilotherm, heterotherm and homeothermic refer/relate to?

A

Whether or not the animal is capable of controlling body temperature.

43
Q

Core temperature

A

37 degrees in humans
The core temperature in humans includes the organs of the thorax, abdomen and the head.
This is where the vital organs are located.
Their enzyme systems must operate in optimum conditions.
The periphery of the body can withstand some deviation from the core temperature.

44
Q

How is heat gained?

A

By conduction from warm air surrounding the body.
By the body’s metabolic activity which generates heat eg: when muscles move.
Humans can also affect their body temperature by changing their behaviour eg: wearing clothes, going into the sun

45
Q

How is heat lost?

A

By conduction and radiation to cold air (or water).
By evaporation of sweat from the body surface.
Humans can also affect their body temperature by changing their behaviour eg: wearing clothes, seeking shade

46
Q

Integumentary system in thermoregulation

Organs of the thermoregulation in the skin:

A

Sweat glands
Arrector pill muscle
Vasodilation/vasoconstriction

47
Q

Maintaining body temperature: keeping warm

A

Increased insulation, subcutaneous fat reduces the condition of heat from the body.
Reduced sweating decreases evaporation.
Increased shivering, increases heat produced by muscle 2 to 5 times.

48
Q

Maintaining body temperature: staying cool

A

Increase blood flow to skin, increases conduction and radiation of heat from the body.
Increased sweat secretion, increases evaporation.
Reduced activity.

49
Q

Gland: Adrenal cortex
Hormone:
Target cell/organs:
Function:

A

Gland: Adrenal cortex
Hormone: glucorticoids, mineralcorticoids
Target cell/organs: many cell types, kidney tubes
Function: promotes synthesis of glucose, regulates reabsorption of salts

50
Q

Gland: Adrenal medulla
Hormone:
Target cell/organs:
Function:

A

Gland: Adrenal medulla
Hormone: adrenaline
Target cell/organs: heart, blood vessel, liver, fat
Function: increases cardiac output, mobilises glucose, prepares body for action

51
Q

Gland: Anterior pituitary
Hormones:
Target cell/organs:
Function:

A

Gland: Anterior pituitary
Hormone: adrenocorticotrophic hormone (ACTH)
Target cell/organs: adrenal cortex
Function: promotes release of adrenal cortex hormones
Hormone: growth stimulating hormone (GSH)
Target cell/organs: bone, muscle
Function: promotes protein synthesis and growth
Hormone: follicle stimulating hormone (FSH)
Target cell/organs: ovary
Function: promotes development of follicle, and secretion of oestrogen
Hormone: luteinising hormone (LH)
Target cell/organs: ovary
Function: promotes ovulation, development of corpus luteum, and secretion of progesterone
Hormone: prolactin
Target cell/organs: mammary glands
Function: stimulates milk secretion
Hormone: thyroid stimulating hormone (TSH)
Target cell/organs: thyroid
Function: promotes production and release of thyroxine

52
Q

Gland: Huypothalamus
Hormones:
Target cell/organs:
Function:

A

Gland: Hypothalamus
Hormones: several releasing hormones
Target cell/organs: anterior pituitary
Function: controls release of anterior pituitary hormones

53
Q

Gland: Ovary
Hormone:
Target cell/organs:
Function:

A

Gland: Ovary
Hormone: oestrogen
Target cell/organs: reproductive tract, body generally
Function: promotes menstruation cycle, development of female features and behaviour

54
Q

Gland:
Hormone:
Target cell/organs:
Function:

A

Gland:
Hormone: progesterone
Target cell/organs: uterus
Function: prepare uterus for, and maintains, pregnancy

55
Q

Gland: Pancreas
Hormone:
Target cell/organs:
Function:

A 
Gland: Pancreas
Hormone: insulin
Target cell/organs: muscle, liver, fat
Function: lowers blood glucose 
Hormone: glucagon
Target cell/organs: liver, fat
Function: raises blood pressure
56
Q

Gland: Parathyroid
Hormone:
Target cell/organs:
Function:

A

Gland: Parathyroid
Hormone: parathyroid hormone
Target cell/organs: bone, kidney
Function: raises blood calcium

57
Q

Gland: Posterior pituitary
Hormone:
Target cell/organs:
Function:

A 
Gland: Posterior pituitary 
Hormone: oxytocin
Target cell/organs: mammary gland
Function: causes release of milk
Hormones: antidiuretic hormone (ADH)
Target cell/organs: kidney
Function: promotes reabsorption of water from the collecting tubule
58
Q

Gland: Pineal
Hormone:
Target cell/organs:
Function:

A

Gland: Pineal
Hormone: melatonin
Target cell/organs: brain
Function: daily and seasonal changes

59
Q

Gland: Testis
Hormone:
Target cell/organs:
Function:

A

Gland: Testis
Hormone: testosterone
Target cell/organs: reproductive tract, body generally
Function: development of masculine features and behaviour

60
Q

Shirt day plants

A

Require long nights to trigger flowering.

Flowering would occur naturally in late summer, autumn or winter.

61
Q

Long day plants

A

Will flower if the nights are short or if the plants are continuously illuminated.
Naturally flower during late spring and early summer.

62
Q

Neutral plants

A

Largely unaffected by day length for flowering to occur.

63
Q

Gland: Thyroid
Hormone:
Target cell/organs:
Function:

A

Gland: Thyroid
Hormone: thyroxine
Target cell/organs: most cells
Function: regulates cellular metabolic rate

Biology Semester Two (7 decks)

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