Topic 5 Functioning Systems Flashcards
1
Q
What is a specialised cell?
A
A cell in a multicellular organism that specialises in form and function so that they perform various functions that serve the needs of the whole organism.
2
Q
How do specialised cells compare with cells of unicellular organisms?
A
A specialised cell of a multicellular organism performs fewer functions but has lost the ability for independent living. In contrast to the single cell of a unicellular organism that can perform all the functions needed to stay alive.
3
Q
What are the levels of organisation?
A
Cell-basic structural and functional unit
Tissue-group of similar cells carrying out same functions
Organ-groups of tissues working together for the same functions
System-groups of organs serving a particular function
4
Q
What are the specialised plant cells?
A
Guard cells Pollen grains Palisade parenchyma Epidermal cell Vessel element Sieve tube cell Root hair cell
5
Q
What is the function of a guard cell?
A
A pair of curved cells that surround a stoma, becoming larger or smaller according to air pressure within the cells
6
Q
What is the function of a pollen grain?
A
Houses gametes, sperm for sexual reproduction
7
Q
What is the function of palisade parenchyma cells?
A
Photosynthetic cells of the leaf
8
Q
What is the function of the epidermal cell?
A
Top layer of a leaf, prevent water loss
9
Q
What is the function of a vessel element?
A
Move water and ions from the root to the leaves where photosynthesis occurs.
10
Q
What is the function of a sieve tube cell?
A
Responsible for transport of sugar
11
Q
What is the function of a root hair cell?
A
Facilitates the uptake of water and ions.
12
Q
What are the specialised animal cells?
A
White blood cells Red blood cells Skeletal muscle cell Egg cell Sperm cell Motor neurone cell Pancreatic cell Epithelial cell
13
Q
What is the function of white blood cells?
A
Cell of the immune system that are involved in protecting the body against infections diseases and foreign invaders.
14
Q
What is the function of a red blood cell?
A
Transport oxygen, remove carbon dioxide from the body transporting it to the lungs for exhalation
15
Q
What is the function of an egg cell?
A
To join with male cells and provide food for the new cells to be formed.
16
Q
What is the function of a skeletal muscle cell?
A
Specialised for voluntary movement
17
Q
What is the function of a motor neurone cell?
A
To carry nerve impulses to different parts of the body.
18
Q
What is the function of a sperm cell?
A
Fertilises female eggs
19
Q
What’s the function of a pancreatic cell?
A
Synthesise and release digestive enzymes
20
Q
What is excretion?
A
The removal of unwanted, excess or toxic metabolic products from an organism.
21
Q
Why is it important to eliminate wastes from the body?
A
They can be harmful or will interfere with normal metabolism if they build up.
22
Q
What are some examples of wastes?
A
Urea, ammonia, excess water and carbon dioxide
23
Q
What is the major source of n wastes for mammals?
A
Dietary proteins
24
Q
How are nitrogenous wastes dealt with in the human body?
A
The proteins in food are broken down into their amino acid subunits through indigestion.
After absorption into the body, these amino acids are used to build a mammals on proteins as part of growth and repair.
25
What happens to excess amino acids?
They cannot be stored and are transported to the liver where they are dissected into two parts in a process called deamination.
26
What happens in deamination?
The n containing part of each amino acid is removed as ammonia (nh3). The remaining part, known as a carbon skeleton is used as a source of energy in aerobic respiration or conversion to glucose. The ammonia that is produced by the deamination in liver cells is immediately converted to urea and is the form in which most n wastes of mammals are excreted.
27
Why is ammonia converted to urea?
Because it is less toxic that ammonia and can therefore be stored in the body until it is convenient to eliminate it.
28
What are other sources of n wastes in mammals?
Other n wastes come from the breakdown of nucleic acids into their nucleotide subunits and from metabolic activity of skeletal muscle that generates creatine and its derivative, creatine
29
What are the major organs of the urinary system?
```
Bladder
Liver
Kidney
Uretha
Ureter
Aorta
Vena cave
```
30
What are the three functions of the kidney?
1. Filter wastes from the blood such as urea, excess water, ions toxins
2. Excrete hormones and other substances (vitamins for eg) that would otherwise build up in the blood stream.
3. Maintain the correct balance of water and ions which help maintain the ph of blood and suitable blood pressure.
31
What is the function of the bladder?
A hollow organ that stores urine until it is excreted.
32
What is the function of the kidney?
Two organs that take waste from the blood and produce urine.
33
What is the function of the ureter?
Two tubes, each of which carries urine from the kidney to the bladder.
34
What is the function of the urethra
The tube that carries urine from the bladder to the outside of the body.
35
What is the function of the aorta?
Transports blood to the kidney
36
What is the function of the vena cava?
Transport blood away from the kidney.
37
What is the function and location of the glomerulus?
Function: network of capillaries carrying blood under high pressure in bowmans capsule of the nephron.
Location: cortex
38
What is the function and location of Bowman's capsule?
Function: collects primary filtrate (nitrogenous wastes and other small soluble molecules but not cells) forced by high pressure
Location: cortex
39
What is the function and location of the proximal tubule?
Function: site of selective reabsorption of useful substances, such as water, glucose amino acids, salts.
Location: cortex
40
What is the function and location of the loop of henle?
Function: active concentration is used to establish salt concentration to enhance water reabsorption.
Location: medulla
41
What is the function and location of the distal tubule?
Function: tubular reabsorption of substances such as sodium by active transport (water follows by osmosis)
Location: cortex
42
What is the function and location of the collecting duct?
Function: reabsorption of water by osmosis so that concentrated urine leaves the nephron
Location: cortex and medulla
43
What are the three steps in which urine is produced?
Filtration
Reabsorption
Secretion
44
Where does filtration occur in the nephron?
Glomerulus
| Bowman's capsule
45
What happens during filtration?
Blood in the glomerular capillaries is under high pressure. Substances are forced through the capillary walls of the glomerulus and through the inner walls of bow,and capsule. About one fifth of the plasma that passes through the glomerulus is filtered through the capsule into the tubule.
46
What substances can be removed or reabsorbed in filtration?
Water and n wastes are removed (urea) nutrients such as glucose, amino acids, drugs, salts, become part of the filtrate. Large proteins and blood cells do not make it through the glomerulus and inner walls of Bowman's capsule.
47
Where does reabsorption take place in the nephron?
Proximal tubule
Loop of henle
Distal tubule
48
What happens during reabsorption?
Some of the molecules that have been filtered through the glomerulus are reabsorbed back into the capillaries. Molecules move back into the blood stream via diffusion (passive) transport and active transport.
49
What substances are removed or reabsorbed in reabsorption?
Reabsorbed: useful nutrients, fatty acids via active transport.
Glucose is reabsorbed via active transport as well as ions (salts). Water follows via osmosis.
50
Where does secretion occur in the nephron?
Collecting tubule.
51
What happens during secretion?
Concentration of urine occurs where the amount of water that is reabsorbed depends on the amount that is consumed, the activities of the organism, diet (high salt vs low salt)
52
What substances are removed or reabsorbed in secretion?
```
Removed with urine
Drugs
Poisons
Urea
Excess ions (salts)
Water
Hydrogen ions
Hormones
```
53
In kidney dialysis why is the dialysing solution constantly replaced from the body?
To remove wastes from the body.
54
Why don't ions such as potassium and sodium and small molecules like glucose diffuse rapidly from the blood into the dialysing solute along with the urea?
As they move against their concentration gradient.
55
Why does urea pass from the blood into the dialysing solution?
The urea is passed from the blood into the dialysis bag which is constantly replaced.
56
What is the transport process involved in dialysis?
Diffusion
57
Why does the dialysing solution flow in the opposite direction to the blood?
The solution is being taken out of the blood to be replaced and then pumped to the heart.
58
Why is a dot and bubble trap needed after the blood has been dialysed but before it enters the body?
Bubbles and clots are dangerous if introduced to the bloods flow.
59
What is the function of xylem tissue?
Water and inorganic mineral ions are transported from the roots to the plants and leaves.
60
What is the structure of xylem tissue?
Xylem tissue is composed of vessel elements and tracheids. Different species of plants may depend on one or more types of cells.
61
What are the properties of vessel elements?
Cylindrical cells orientated end to end
At maturity the end walls of these cells dissolve away and the cytoplasmic contents die, therefore these cells are dead.
Their walls are thickened with secondary deposits of cellulose.
Further strengthened by impregnation with lignin.
The secondary walls or xylem vessels are deposited in spirals and rings and are perforated by pits.
62
What are the properties of tracheids?
Cells tapered end to end so the tapered end of one cell overlaps that of the adjacent cells
Have thick, lignified cells.
At maturity, no cytoplasm therefore they are dead.
Their walls are perforate so that water can flow from one tracheids to the next.
63
What happens to older xylem in woody plants?
It ceases to participate in water transport and simply serves to give strength to the trunk. Wood is xylem, therefore the annual rings of a tree are actually rings of xylem.
64
What is the function of phloem tissue?
Transport sucrose and other organic molecules. Sucrose is transported from the leaves where it is produced (source) and translocated to the places where it is consumed or stored (sinks). Such as roots, growing tips of stems and leaves, flowers and fruits.
65
What is the structure of phloem tissue?
Composed of sieve elements and companion cells.
66
What are the properties of sieve elements?
The end walls of these cells are perforated, this is called the sieve plate.
This allows cytoplasmic connections between vertically stacked cells.
The result is a sieve tube which conducts the products of photosynthesis (sugars and amino acids).
Has no nucleus and very few organelles.
At maturity these cells are alive.
67
What are the properties of companion cells?
Found adjacent to the sieve tube cells.
Responsible for keeping the phloem cell alive.
It has nucleus, mitochondria and other organelles.
Intense metabolic activity, one of which provides energy for transport processes.
68
In xylem and phloem cells, what is transported?
Xylem: water and inorganic mineral ions
Phloem: sucrose and organic molecules
69
What is the direction of transport in xylem and phloem?
Xylem: roots to leaves
Phloem: leaves to roots, flowers, stems, fruits (source to sink)
70
What is the energy source for transport?
Xylem: transpiration and root pressure draw water upwards (no ATP)
Phloem: active transport, ATP
71
What is the cell type involved in transport? In xylem and phloem cells
Xylem: vessel elements and tracheids
Phloem: sieve elements and companion cells
72
In xylem and phloem cells what is the relative cell diameter?
Xylem: larger
Phloem: cross sectional diameter is narrower that xylem
73
In xylem and phloem cells what is the relative cell wall thickness and composition?
Xylem: thick strengthened with cellulose and lignin
Phloem: less thick
74
In xylem and phloem cells what is the cell arrangement?
Xylem: arranged end on end to create a tube
Phloem: sieve cells arranged end on end to create a tube.
75
In xylem and phloem cells are pits present?
Xylem: yes
Phloem: no
76
In xylem and phloem cells are the cells living or dead?
Xylem: dead
Phloem: living
77
In xylem and phloem cells what is their other function?
Xylem: provide support and structure for the stem of the plant
Phloem: also transport hormones around the plant
78
What is the function of cambium?
Growing of undifferentiated cells that will become either xylem or phloem.
79
What are the two mechanisms plants use to absorb nutrients?
Diffusion: passive transport of minerals and water through osmosis
Active transport: mineral ions into roots against concentration gradient
80
Plants take up water constantly to compensate for water lose in transpiration. What is the benefit of a large water uptake?
Water is transported which passively absorbs mineral ions along with it. Mineral ions and transported for metabolic use. Water keeps the cells turgid and provides minerals needed for the manufacture of food.
81
How does root pressure assist in water uptake?
Osmosis: high concentration of water outside, low concentration inside, movement creates by concentration gradient.
82
What are the main components of the leaf?
```
Cuticle
Upper epidermis
Palisade mesophyll
Small vein
Spongy mesophyll
Lower epidermis
```
83
What is a cuticle?
A transparent, waxy waterproof layer.
84
What is the upper epidermis?
A single layer of cells forming the upper skin. In surface view the cells are irregular in shape.
85
What is the palisade mesophyll?
One or two layers of regularly spaced brick shaped cells which contain lots of chloroplasts.
86
What is the small vein?
Contains long tubular cells, vessels for water transport and sieve tubes for food transport and other rigid cells for strengthening.
87
What is the spongy mesophyll?
Rounded cells, packed very loosely together with large air spaces between them. The cells contain chloroplasts in smaller numbers than the palisade mesophyll.
88
What is the lower epidermis?
Similar to the upper epidermis but with a thinner cuticle and with numerous stomata.
89
What is transpiration?
Loss of water from the surface of plants, usually through the stomata of leaves.
90
What are cohesion forces?
The force of attraction of water molecules for one another which also helps to support the column as it it pulled up by the xylem.
91
What are adhesion forces?
Adhesion force-surface tension-capillary
Adhesion is the force of attraction between water and cellulose fibres. The narrower the vessel the greater the force of attraction so the greater the surface tension. Xylem have microscopic diameter with thigh cells walls and cellulose fibres so there is a large sa of cellulose in contact with a small amount of water so the surface tension is high. This force helps to support the thin water column and prevents it from snapping apart when it is pulled up the xylem.
92
What is root pressure?
In plants, a force that helps drive fluids upwards into the xylem generated by osmotic pressure in the cells of the roots.
93
What factors affect the rate of transpiration?
```
Light
Temperature
Wind
Humidity
Cuticle thickness
```
94
What 3 steps allow water to move from the roots to leaves due to transpiration?
1. Movement of water out of the leaf by transpiration
2. Water moves into cell walls in the leaf due to cohesion and surface tension.
3. Water moves into the root along an osmotic gradient.
95
How does water move out of a cell?
Open stomata allows leaves to lose water via evaporation. Water in the leaf evaporates from the surface of mesophyll cells into the intracellular spaces. Water gains heat energy from the sun and becomes a gas to overcome surface tension and cohesion between the water and cellulose on the mesophylls cell surface. Humidity rises which creates a diffusion gradient between the sides of the leaf. Water vapour diffuses our via stomata. As water escapes, the humidity in the intracellular space falls and causes more water to evaporate, thereby repeating the process.
96
How does water move onto the cell walls in the leaf?
Cohesive bonds mean water sticks together. After water evaporates from cells walls of mesophyll cells to intracellular spaces in the leaf, surface tension and cohesion cause other water molecules to replace them which is taken out of xylem vessels. This movement of water is then transmitted down the xylem, cohesion causing it to for, a column. As the molecules at the head of the column move into the leaf, the ones behind move up to take their place.
97
How does water move into the root?
Water enters root hair cells of a plant by osmosis as the solute concentration inside the cells is higher than that of soil water. Active transport maintains high solute levels in the cells, so water can move into them via osmosis. These water molecules replace those that move out of the root cells into the xylem vessel. With the root, much of the water passes along cell walls until it reaches the endodermis. The caspian strip is impervious to water and water passing into the endodermal cells must move via the cytoplasm which stops the way column from draining out the xylem vessels. After leaving the endodermis, water passes through more cells on route to the xylem which it then enters, replacing the water that has moved up the column.
98
What is translocation?
The transport of sucrose and other organic material thought he phloem of a vascular plant.
99
How is sucrose translocated from the leaves to the phloem?
The product of photosynthesis are the source of organic molecules for all parts pf the plant. Sugars are actively transported, mainly as a sucrose from leaves to other parts of the plant via sieve tubes. This energy is provided by companion cells, as the concentration of sugar in phloem increases water moves from the xylem by osmosis into the sieve tubes which increases their pressure.
100
How does sucrose exit the phloem?
Sugar is actively transported to the phloem where it is stored as starch broken down into monosaccharides used in metabolism. Parts of a plant that use organic material made elsewhere in the plant are called sinks. It increases the concentration of water in the sieve tube in that region, so water moves out of the sieve tube. The loss of water from the sieve tube close to the sinks results in a decreased pressure in the sieve tubes in that region.
101
How does the difference in pressure facilitate translocation?
A region of high pressure exists in sieve tubes near the sugar source and a region of low pressure exists near the sugar sink. This difference in pressure pushes sugar rich sap through the sieve tube colours from the sources to the sinks.
102
When sugar arrives at sinks, how is it used?
It is stored as starch
Used as sub units for building structural components of cells
Used as energy for cellular respiration
103
How do stomata open or close?
The stomata open or close depending on the turgor of the guard cells. If the guard cells have a high water content when they are turgid and the pore is open. As the guard cells lose water they become more flaccid and the pore closes.
104
What are the special features of guard cells?
The wall adjacent to the pore is thicker than the wall away from the pore.
There are a number of cellulose microfibres in guard cells and these are oriented in a way that makes the wall adjacent to the pore less elastic than the wall away from the pore.
Chloroplasts are present.
When water enters the guard cells the walls away from the pore stretched more than the inner wall and this results in and oval pore appearing in the centre as the two guard cells expand.
105
How does water enter guard cells?
When carbon dioxide concentration declines, photosynthesis commences as light become available.
This change results in a significant number on ions particularly k ions moving into guard cells.
Water follows via osmosis.
106
How do stomata close?
Increase in co2 as photosynthesis ceases because light decreases
Potassium ions diffuse out of guard cells
H2o moves out of guard cells via osmosis
Guard cells become flaccid
Stomata close
107
How do stomata open?
```
Photosynthesis decreases co2 as light increase
Potassium ions diffuse into guard cells
H2o follows via osmosis
Guard cells become turgid
Stomata open
```
108
What three gases are exchanged by plants?
Carbon dioxide, oxygen, water vapour
109
Where does gas exchange occur?
Through open stomata
110
Where is photosynthesis carried out in plants?
Palisade cells in leaves
111
What happens to co2 levels during the day?
Plants carry out more photosynthesis than respiration which results in a cellular co2 level rise in palisade cells.
112
Why will co2 diffuse into the leaf from the air?
There is a higher concentration of co2 outside and a low concentration inside the lead as it will be used up in photosynthesis.
113
Why will oxygen diffuse out of the leaf from the air spaces?
There is a higher concentration of oxygen inside the leaf because it is being produced via photosynthesis and a lower concentration outside.
114
During transpiration how does water evaporate from a plants surface from leaves through open stomata?
Within the leaf, water evaporates from the surface of cells into the intracellular spaces forming water vapour.
What vapour then diffuses out of the intracellular space into the air.
115
Why does transpiration occur more slowly in humid condition?
There is a greater concentration of water vapour outside resulting in a decreasing concentration gradient which results in water loss.
116
Why does transpiration occur more rapidly in hot conditions?
The gas particles are moving faster, leaving the stomata quickly and increasing the rate of water loss.
117
Why does transpiration occur more rapidly in windy conditions?
The wind blows away the gases and lowers air pressure, steepening the concentration gradient and causing the plant to lose water and water water is replaced.
