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AOS2 Flashcards

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Biology 101 flashcards
1
Q

level of organisation

A 
Organism
System
Organs
Tissue
Specialised cells
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2
Q

all organisms need to do the following 6 funtions

A
  1. take in nutrients and water
  2. exchange gases
  3. remove waste
  4. obtain energy
  5. reproduce
  6. grow
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3
Q

specialised cells

A

cells that have a specific function and have unique structural adaptations eg: muscle cell

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4
Q

Tissues

A

groups of similar specialised cells that work together to carry out a function eg: muscle tissue

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5
Q

Organs

A

two or more tissues that group together to perform a task they have distinct structure eg: heart

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6
Q

Systems

A

organs that work together to form an organ system eg: circulating nutrients

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7
Q

vascular plant

A

have their own circulatory system called the vascular system

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8
Q

purpose of the vascular system

A
  1. gather water
  2. transport gases
  3. transport nutrients
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9
Q

root hair cells

A

roots of plants that absorb water from the soil, they have a branched structure to increase their SA hence increasing absorption efficiency

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10
Q

stomata

A

tiny pores in plant tissue through which gas exchange occurs. It allows water vapour and oxygen out and carbon dioxide into the leaf.

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11
Q

guard cells

A

specialised cells that surround the stomata they open and close the stomata pores depending on the gas exchange and water needs of the plant

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12
Q

two types of vascular plant tissue

A
  1. xylem

2. phloem

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13
Q

Xylem

A

movement of water from the roots to the rest of the plant through a process called transpiration

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14
Q

transpiration

A

passive movement of water

  1. heat energy causes evaporation of water in the leaves through the stomata
  2. the internal pressure of the xylem vessels is reduced (low pressure) which generates a pulling force
  3. it pulls water up from the roots against the force of gravity to replace the lost water
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15
Q

purpose of transpiration

A
  1. absorb necessary water
  2. transport minerals
  3. cool down
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16
Q

Phloem

A

transports organic solutes from (source) leaves to (sink) roots and other tissues; enables molecules to travel in more than one direction such as; sugar through a process called translocation

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17
Q

structure of the phloem

A

cells in the phloem tissue form rows called sieve tubes

their wall is perforated this forms sieve plates

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18
Q

translocation

A

active process of moving sugars from leaves to other tissues in the plant. Sucrose is pumped into companion cells which move into the sieve tube cells.

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19
Q

leaf is the site of what

A

gas exchange

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20
Q

when guard cells are turgid what are the pores

A

open

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21
Q

when guard cells are flaccid what are the pores

A

closed

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22
Q

what pressure is generated from the loss of water from the leaves

A

a negative presure which creates a pulling force pulling up more water to replaced the lost

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23
Q

name the two paths water molecules can travel

A

symplastic/cytoplasmic pathway-through the cells

apoplastic/extracellular pathway-via cell walls

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24
Q

name 4 stimulants for an affect on transpiration rate

A

light=increased rate
temp=increased rate
wind=increased rate
humidity=decreased rate

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25
Q

xerophytes

A

live in environments with a shortage of water

  • shortage of leaves
  • low growth
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26
Q

define homeostasis

A

maintenance of a stable internal environment (fluid surrounding the cell) despite changes to the external environment (rest of the body)

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27
Q

tolerance range

A

greater the ability to regulate

28
Q

stages of homeostasis

A

stage 1: detection of change from a stable state by receptors
stage 2: receptors stimulate a response to this change by effectors

29
Q

the loss of water vapour is called what

A

transpiration

30
Q

how do plants minimise water loss

A

by using guard cells to open and close the stomata

31
Q

stomata tend to be open and closed when

A

open during the day and closed during the night

32
Q

3 forces that water is under in the xylem tubes

A

a pulling force exerted by transpiration in the leaves
a pushing force exerted by osmosis
adhesion and cohesion forces of water molecules (unbroken stream called transpiration stream)

33
Q

xylem cells are what

A

dead cells-no cellular components

34
Q

compared to atmospheric pressure the xylem vessels are what

A

much lower-they can withstand low pressures due to their thick vessels

35
Q

water molecules are cohesive between each other due to what

A

hydrogen bonding

36
Q

water molecules are adhesive to the hydrophilic cellulose fibres in the xylem walls due to what

A

hydrogen bonding

37
Q

how does water move between cells

A

osmosis from high water concentration to low water concentration

38
Q

what is the only energy required for the transpiration pull process

A

heat energy that causes the evaporation of water from the leaves

39
Q

where does translocation transport first occur

A

areas of new growth

40
Q

adhesion

A

Adhesion is the force of attraction between two particles of different substances (e.g. water molecule and xylem wall)

41
Q

cohesion

A

force of attraction between two particles of the same substance (e.g. between two water molecules)

42
Q

vascular bundle

A

the grouping of xylem and phloem vessels in a plant

43
Q

Chemical digestion

A

break down of food molecules by digestive enzymes

44
Q

negative feedback loops

A

Negative feedback are mechanisms that counteract the stimulus to bring a condition back to normal (restores original state).

45
Q

Negative feedback loop caused by drop in glucose levels

A

Chemoreceptors in the pancreas detect change and release glucagon from the pancreas which causes the breakdown of glycogen to glucose in the liver, increasing glucose levels back to normal

46
Q

what are hormones responsible for

A

the communication between tissues and organs

47
Q

positive feedback

A

A type of regulation that responds to a stimulus by initiating responses that will increase the stimulus.
eg: release of oxytocin during childbirth to stimulate contractions

48
Q

What is faster? The hormonal or the nervous system?

A

The hormonal system is slower than the nervous system because the molecules have to be passed through the blood or tissue to reach the target cells, where as nerve action occurs due to electrical impulses

49
Q

what lasts longer? The hormonal or the nervous system

A

Hormonal system action is more sustained than the nervous system because hormones must be metabolised before inactivation occurs.

50
Q

Chemoreceptors

A

Stimulated by chemical changes eg: taste, smell, blood ph

51
Q

Mechanorecpetors

A

stimulated by forces or pressure e.g. sound, touch, vibration

52
Q

Photoreceptors

A

Stimulated by light. Located in the retina of the eyes

53
Q

Thermoreceptors

A

Stimulated by temperature changes. Located in the skin and brain and are involved in temperature regulation.

54
Q

The basic structure of a vascular plant contains

A

Leaves (photosynthesis)
Root (to absorb water)
Stem (stability)

55
Q

feedback loop

A

A stimulus-change to a stable state which causes a signal
A receptor-detects the signal from the stimulus
A control centre-is where the signal is transferred to (hypothalamus)
An effector-is where the signal is sent to
A Response-is what the effector works to perform

56
Q

what are phloem sieve tubes controlled by

A

companion cells

57
Q

what does the hormone insulin do

A

stimulates cells to absorb glucose from the blood

58
Q

when do stomata tend to close

A

when it is hot and dry to prevent excess water loss

59
Q

where are stomata found

A

in the epidermis of leaves and some stems

60
Q

what are the two most important systems in maintaining homeostasis in animals

A

endocrine system and the nervous system

61
Q

insulincoh negative feedback loop

A

If glucose levels get too high, the body releases insulin into the bloodstream. Insulin causes the body’s cells to take in and store glucose, lowering the blood glucose concentration. If blood glucose gets too low, the body reduces the release of insluin and releases glucagon, which causes the release of glucose from some of the body’s cells.

62
Q

type 1 diabetes

A

body does not produce sufficient insulin hence glucose is not removed from the blood stream

63
Q

hypoglycaemia

A

blood glucose levels are too low (too much insulin)

64
Q

hyperthyroidism

A

production of too much thyroxine hormone

65
Q

type 2 diabetes

A

it is caused by an ineffective homeostatic repsonse to insulin

66
Q

marram grass

A

roll their leaves to reduce water loss

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