3.3- Organisms exchanging substances Flashcards
1
Q
What needs to be exchanged between an organism and the environment?
A
Oxygen, waste products, nutrients, heat
2
Q
exchange surfaces
A
surfaces over which materials are exchanged from one area to another.
Lungs, roots, leaves, intestines
3
Q
Factors affecting rate of exchange
A
Surface area, temperature, conc gradient
4
Q
how to measure surface area
A
(BxH) x number of sides
5
Q
How to measure volume
A
B x H x L
6
Q
Single Celled Organisms- exchange
A
Can use diffusion alone to provide their nutrients
7
Q
Multi Celled Organisms- exchange
A
Require transport systems and specialised exchange surfaces to provide the cells nutrients
8
Q
What happens as an object gets smaller?
A
The sa:v increases
9
Q
Why can’t insects use their body surface to transport?
A
They are multicellular so have a large distance between cells and outside
10
Q
What can an efficient gas exchange surface also mean?
A
An efficient water loss surface
11
Q
What do terrestrial insects have to do?
A
Balance their needs to conserve water with the need to exchange gases
12
Q
How do insects limit water loss?
A
-small surface area to volume ratio
-waterproof coverings
-spiracles which can close
-Hairs that reduce air movement
13
Q
Tracheae
A
tiny tubes in insect body that deliver oxygen directly to metabolizing tissues
14
Q
Spiracles
A
openings in the abdomen of an insect that are used for breathing- allow gases in and out and controlled by valves
15
Q
Why aren’t insects bigger?
A
More cells=more oxygen demand. Insects wouldn’t be able to meet that oxygen demand
16
Q
Limitations of the tracheal system
A
Insects rely on diffusion rather than a transport system.
It limits the size insects can grow to
17
Q
How do gases move in and out of the tracheal system?
A
Diffusion gradient, muscle contractions, water filled tracheoles
18
Q
Diffusion gradient
A
Respiring cells use oxygen and thus reduces its concentration in the object compared to outside. Same happens to CO2 but in reverse
19
Q
Muscle contraction & the tracheae
A
Squeezing the tracheae through abdominal pumping causes contracting of insect muscle which reduces volume in tracheae and expels air
20
Q
Water filled tracheoles
A
Anaerobic respiration produces lactate which is water soluble- this lowers water potential of muscle cells. Water moves into muscle cells from tracheoles. Volume in tracheole end decreases, draws the air in.
21
Q
What happens when the spiracles close?
A
Oxygen levels decrease in the tracheae as oxygen is used up by the respiration and there is no more entering the tracheae.
22
Q
What causes spiracles to open ?
A
an increase in CO2 as there may be less volume to keep the waste products.
23
Q
What do both plants and animals have to reduce water loss?
A
a waterproof cuticle/surface
24
Q
Are fish adapted to exchange materials via their surface?
A
No they are large and multicellular
25
Coating of fish
Waterproof and gas tight
26
Specialised internal exchange surface in fish
gills
27
Gill structure
Gill cover protects gills.
Gills are made of gill filaments that are stacked on top of each other
Filament is covered in lamellae that are at right angles to the filaments
28
What does parallel flow mean?
Water and blood flow in the same direction in the gills
29
How does water enter the fish?
By the mouth then passed out over the gills
30
countercurrent flow
flow of water opposite that of the flow of blood in a fish's gills
31
Why is parallel flow not beneficial for fish?
the most oxygen rich water meets the least oxygen rich blood meaning lots of diffusion occurs in the beginning and by the middle of the gill, equilibrium is met. Half of the exchange surface is wasted.
32
How is countercurrent flow beneficial for fish?
The most oxygen rich water meets the most oxygen rich blood. This controls the diffusion of oxygen, preventing an equilibrium from being met. A favourable O2 gradient is maintained.
33
Where is there always a higher oxygen concentration?
Water
34
What does countercurrent flow result in?
This results in the maintenance of a favourable O2 gradient across the whole gill.
35
Dicotyledonous plants
Plants that produce seeds that contain two cotyledons. They have two primary leaves.
36
What gases do plants need?
carbon dioxide and oxygen
37
What is the respiration equation?
oxygen + glucose > carbon dioxide + water + energy
38
What is the photosynthesis equation?
Carbon dioxide + water > glucose + oxygen
39
How are the leaves of a plant adapted for gas exchange?
Large Surface Area
Thin
Selectively Permeable
Diffusion Gradient
40
How are plants and animals different in terms of gas exchange?
Plants photosynthesise and respire
41
What reduces the gas exchange with the outside environment?
Gases produced in photosynthesis and respiration are used in other processes. Rates of reaction change the volume and types of gases being exchanged.
42
Gas Exchange in plants during the day
Respiration provides some CO2 for photosynthesis however most of it is taken from the environment. Some O2 from photosynthesis is used in respiration however most diffuses out.
43
Gas exchange in plants at night
Dark. No photosynthesis occurs without light. Respiration still occurs as o2 diffuses into the leaf and CO2 diffuses out.
44
stomata (stoma)
small pores on underside of leaf allow water in and out- also allows co2 and o2 movement
45
Waxy cuticle
Forms a waterproof layer to stop water loss through evaporation
46
Palisade cells
closely packed photosynthetic cells within leaves. Many chloroplasts to trap light
47
Guard cells
control the opening and closing of stomata
48
Xylem
vascular tissue that carries water and minerals upward from the roots to every part of a plant
49
Phloem
Living vascular tissue that carries sugar and organic substances throughout a plant
50
Upper epidermis cells
Upper layer of the cells, covers with a waxy waterproof cuticle that reduces water loss from leaf. Transparent
51
Spongy mesophyll cells
Rounded, loosely packed cells, with air spaces between them. They are found below the palisade cells. Allow gas exchange
52
When do stomata open and close?
open during the day and close at night. Photosynthesis occurs during the day so O2 is required, hence why stoma open
53
How does exchange of gases also cause loss of water in leaves?
Large sa allow lots of gas exchange and absorption of sunlight. This also promotes loss of water through desiccation
54
The Transpiration Stream
the movement of water through a plant from the roots until it is lost by evaporation from the leaves. Happens because of cohesion tension theory
55
cohesion-tension theory
theory that explains how the physical properties of water allow it to move through the xylem of plants- water sticks together.
56
Xerophytes
Plants adapted to living in areas with a short supply of water
57
Adaptations- thick waxy cuticle
Acts as a thick waterproof barrier preventing evaporation and osmosis
58
Adaptations- rolled up leaves
Protects the stomata on lower epidermis. Still, moist air is trapped holding water against the stomata. Water potential gradient is lowered, preventing the movement of water out.
59
Adaptations- hairs on leaves
Still, moist air is trapped holding water against the stomata. Water potential gradient is lowered, preventing the movement of water out.
60
Adaptations- Sunken stomata
Still, moist air is trapped holding water against the stomata. Water potential gradient is lowered, preventing the movement of water out.
61
Adaptations- reduce SA:Vol ratio
Slower rate of diffusion as there is limited space for movement/evaporation of water out the cell. Still allows photosynthesis
62
Why do we breathe?
To get O2 & get rid of CO2, they are equally important during respiration
63
Alveoli structure
- layer of thin flattened epithelial cells → short diffusion pathway
- elastin + collagen → stretch and recoil
- large surface area
- surrounded by capillaries → good blood supply
- good ventilation
64
Structures of the lungs
Trachea, bronchi, bronchioles, alveoli
65
What features allow for fast diffusion?
Slowed rbc, rbc flattened against capillary wall, thin walls, large surface area
66
Difference between epithelial and endothelial
Epithelial- alveoli
Endothelial- capillaries
67
Describe inspiration
* External intercostal muscles contract, pulling the ribcage up and out
* Diaphragm contracts, pulling it from a domed to a flattened shape
* Combined effect is:
Volume of thorax and lungs increases
Pressure is reduced
Air enters and goes down the pressure gradient
68
Where must gases diffuse?
Across the alveoli wall and capillary wall
69
Tuberculosis
An infectious disease that may affect almost all tissues of the body, especially the lung- caused by bacterium
Infection course- inhaled TB bacteria enters lungs and multiplies causing a lung infection- lymph nodes may be enlarged. Immune system reacts by forming scar tissue around bacteria, hardening and thickening tissue
70
Tuberculosis symptoms
productive cough, fatigue, fever, weight loss (anorexia, weight loss) night sweats
71
Pulmonary Fibrosis
formation of scar tissue in the connective tissue of the lungs. An autoimmune disorder. Air sacs of lungs become replaced by fibrotic tissue- making them thicker and increasing diffusion pathway.
72
Pulmonary Fibrosis symptoms
shortness of breath, dry hacking cough, fatigue, chest discomfort or pain
73
Emphysema
a condition in which the air sacs of the lungs are damaged and enlarged, causing breathlessness. Mainly caused by smoking. Tobacco smoke temporarily paralyses the cilia so irritants enter the alveoli and inflame and damage alveoli tissue
74
Emphysema symptoms
shortness of breath, chronic cough, fatigue, excess mucus, blue tint to skin
75
Asthma
episodes of breathing difficulty due to narrowed or obstructed airways. Can be inherited or due to a lack of exposure to certain substances. Can be life threatening if airways are severely restricted
76
Asthma symptoms
shortness of breath, wheezing, coughing, excessive mucus production
77
Digestion
The process by which the body breaks down food into small nutrient molecules. Large insoluble molecules are hydrolysed by enzymes into small soluble molecules which can be absorbed and assimilated
78
Salivary glands
Glands of the mouth that produce saliva, a digestive secretion. Saliva provided to mouth and contains amylase
79
Oesophagus
Carries food to the stomach
80
stomach
Muscular sac- lining produces enzymes. Stores and digests food by having glands
81
Pancreas
Large gland that produces pancreatic juices containing protease, lipase and amylase
82
ileum (small intestine)
Long muscular tube. Walls and glands produce enzymes. Walls folded into villi and microvilli
83
Large intestine
The last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body
84
Rectum
Final section of intestines. Stores faeces which is egressed by the Anus
85
physical digestion
The mechanical breakdown of large food particles into smaller ones. Chewing of food, churning of the stomach
86
Chemical digestion
Enzymes break down food into smaller molecules using hydrolysis. Uses 3 main enzymes: protease, carbohydrase, lipase.
87
Importance of physical digestion?
Larger SA:V ratio which aids enzyme action
88
Lipid digestion
Hydrolysed by lipases. Ester bonds are hydrolysed to form fatty acids and monoglycerides.
Lipids first hydrolysed into micelles and then to fa and mg.
Called emulsification
89
Why does emulsification aid lipid absorption?
Breaks down larger fats into smaller ones therefore increasing surface area. More SA means more space for enzyme actions to occur
90
Bile salts
compounds in bile that aid in emulsification. One side is hydrophilic/lipophobic and the other side is hydrophobic/lipophillic . They prevent the fats from sticking back together
91
Protein digestion
Peptidases hydrolysed peptide bonds in proteins. 3 main forms: endopeptides, exopeptides and dipeptides.
92
Endopeptidases
Hydrolyse in the central region forming smaller polypeptides. Move freely
93
Exopeptidases
Hydrolyse at terminal/end amino acids of the peptide molecules formed by endopeptides. Move freely
94
Dipeptidases
Hydrolyse the bonds between 2 amino acids of a dipeptides. Membrane bound
95
Absorption of triglycerides
Micelles break down when in contact with epithelia cells, releasing monoglycerides and fatty acids (non- polar so diffuse)
Once in epithelial cells, transported to endoplasmic reticulum where they rejoin to form triglycerides
Triglycerides associate with cholestrol and lipoproteins to form Chylomicrons
These move out of E cells by exocytosis, entering lacteals
Chylomicrons pass into blood system
Triglycerides in chylomicrons are hyrdolysed by enzyme and then diffuse into cells
96
Chylomicrons
Small milky globules. Fat globules composed of proteins and lipids. Transport fat from the intestine to adipose tissue.
97
Explain how the structure of the ileum is adapted to maximise exchange (5 marks)
Villi and Microvilli- hair like structures, folds of the cell walls. Increases the surface area so there is more space for exchange to occur.
Muscles layers- maintain the concentration gradient by constantly pushing food through ileum. Means there is a constant stream of nutrients that can diffuse
Capillary bed- Maintain concentration gradient of the bloodstream by meaning there is always a constant blood supply
Thin walls lined with epithelial cells- ensure a short diffusion pathway
98
Describe the process of co-transport
-Sodium is actively transported into the blood by the sodium potassium pump. Potassium leaves the blood and enters the cell
-Now a high concentration of sodium in the lumen compared to epithelial cell. Sodium diffuses into the cell
-When sodium diffuses in, it brings aa or glucose with it
-Glucose/AAs pass into the blood plasma by facilitated diffusion
