Modes of nutrition Flashcards
1
Q
Modes of nutrition:
A
2
Q
A
3
Q
A
4
Q
Living organisms need a source of energy and raw materials in order to survive
A
grow and reproduce.
5
Q
A
6
Q
- Autotrophic - This is where organisms create complex organic chemicals from inorganic substances
A
using an energy source.
7
Q
- Photoautotrophic - This is where light energy is used to combine inorganic substances to create complex organic chemicals (e.g. photosynthesis).
A
8
Q
- Chemoautotrophic - Uses chemical energy (from chemical substances) in order to combine inorganic substances into complex organic chemicals.
A
9
Q
- Heterotrophic - Organisms which cannot produce their own organic chemicals; must instead digest organic chemicals which have been produced by other organisms
A
and use the products of digestion to synthesise their own organic chemicals.
10
Q
- Saprotrophic/saprobiontic - Involves extracellular digestion of dead or decayed organic matte: enzymes are secreted by an organism which will then digest the organic chemicals of the substrate on which they live. The products of digestion are then absorbed by the saprotroph.
A
11
Q
- Holozoic - Absorption of organic matter followed by internal digestion of the organic chemicals
A
within the organism. In single celled organisms
12
Q
- Parasitic - Living in or on another organism
A
whereby nourishment is obtained from a host organism
13
Q
- Symbiosis/mutualism - Many organisms live in or on other organisms in a relationship which provides benefit to both organisms.
A
14
Q
A
15
Q
A
16
Q
A
17
Q
A
18
Q
A
19
Q
All photoautotrophic organisms are able to carry our photosynthesis
A
which involves combining carbon dioxide and water to produce their own organic compounds. Photosynthesis uses energy from photons of light
20
Q
Carbon dioxide + water -> glucose + oxygen
A
21
Q
- Light energy is transferred to carbon containing compounds as chemical energy.
A
22
Q
- By the addition of atoms of other elements
A
photoautotrophs are able to produce all the organic compounds needed for the organism to grow and reproduce.
23
Q
![[Pasted image 20250225163118.png|400]]
A
24
Q
A
25
#### Chemoautotrophs:
26
27
Chemoautotrophs are also able to combine inorganic substances to produce organic compounds
but they instead use energy from chemicals (not light) to allow this to take place. Many of these organisms are members of Achaea
28
- **Pyrolobus** - extreme thermophile living in temperatures of more than 100 degrees C
29
- **Methanococcus** - lives in the stomach of a cow and uses ethanoic acid as an energy source
30
Some bacteria are also chemoautotrophs:
31
- **Nitrosomonas** - obtain their energy from ammonia
32
- **Methylaminos** - oxidises methane as a source of energy
33
34
## Heterotrophic nutrition:
35
36
#### Saprotrophic nutrition:
37
38
All animals and fungi as well as many bacteria and archaea
are **heterotrophic**
39
- Carbon
for making organic chemicals
40
- Nitrogen
for making proteins and nucleic acids
41
- Phosphate
for making ATP
42
- Vitamins and minerals for making a wide range of biochemicals
43
- Energy
44
45
One form of heterotrophic nutrition is saprotrophic nutrition:
46
47
- In saprotrophic nutrition
extracellular enzymes are secreted from the organism
48
- Fungi and bacteria are the main examples of organisms that have saprotrophic nutrition.
49
50
Fungi
and moulds are responsible for the breakdown of large volumes of dead
51
- They grow as **hyphae**
microscopic fibres which may have distinct cell walls between adjacent cells
52
53
#### Parasitic nutrition:
54
55
Parasites are:
56
- organisms that live in (endoparasites) or on (ectoparasites) another organism
57
- They obtain nourishment at the expense of the hist
58
- Usually cause harm to the host
59
Animals which are parasites are usually highly specialised to be able to survive
obtain nutrition in or on the host organism.
60
- The **PRIMARY** host organism is where the adult forms of the parasite develop
61
- **SECONDARY** hosts are where larval/intermediate forms of the parasite are found
62
- **VECTORS** are secondary hosts which actively and directly transfer the parasite from one primary host to another primary host (e.g. malaria).
63
The **pork tapeworm (Taenia solium)** and the **beef tapeworm (Taenia saginata)** are examples of endoparasites.
64
![[Pasted image 20250225165219.png]]
65
66
>**Tapeworms have several structural adaptations to enable them to live in the digestive system of an animals**:
67
>- The head of the tapeworm is called the scolex - this embedded in the gut wall and has hooks and suckers to prevent it being dislodged by **peristalsis**.
68
>- There is no digestive system or mouth as the tapeworm only needs to absorb nutrients that have already been digested.
69
>- The body is flat to increase the surface area for absorption of nutrients from the gut contents.
70
>- Each proglottid is covered in a thick cuticle which is resistant to the action of digestive enzymes. They also secrete mucus and enzyme inhibitors to reduce the risk of digestion.
71
>- Respiration is anaerobic as there is no oxygen in the gut lumen.
72
>- Each proglottid is hermaphrodite containing both male and female reproductive organs - it therefore does not need a mate as it can self-fertilise. Each proglottid can contain about 50
000 eggs
73
>![[Pasted image 20250225165732.png]]
74
75
76
The **headlouse** is an example of an ectoparasite. It lives on the head
where it clings to hairs using strong claws. Eggs are laid and glued to the base of hairs - when empty they are white (nits). Both adults and larval stages of headlice feed on blood.
77
- Head lice are obligate parasites
and can only live in human hair. They have no vectors
78
79
Plants can also be parasitic; some
such as **dodder**
80
- Mistletoe is semi-parasitic. Its roots penetrate the xylem and the phloem of the host plant
but it also has leaves which can carry out photosynthesis.
81
82
#### Holozoic nutrition:
83
84
Many organisms have evolved different
more complex
85
- This means that an organism does not need to be attached to its food source in order to digest it; it can ingest its food and then digest it somewhere else. The products of digestion are then absorbed
assimilated and waste is egested.
86
87
>**Single-celled holozoic organisms**:
88
>- Amoeba are single-celled organisms that ingest and digest food
89
>![[Pasted image 20250225170636.png]]
90
>- This is an example of **intracellular digestion**; food particles are ingested through endocytosis/phagocytosis and undigested food/waste products are expelled through exocytosis.
91
92
>**Multicellular holozoic animals:**
93
>- Multicellular organisms show increasing levels of organisation which enable them to digest a wider range of foods and digest them more efficiently.
94
>- They have a digestive system
which carry out extracellular digestion
