1. The Nature and Variety of Living Organisms

Characteristics of living organisms, Eukaryotic organisms, Prokaryotic organisms, Pathogens

what characteristics must something have to be considered ‘living’? what do they mean?

M - movement

R - respiration

S - sensitivity

G - growth

R - reproduction

E - excretion

N - nutrition

C - control

what is nutrition? (mrs gren)

organisms must obtain food to provide energy

what is respiration? (mrs gren)

respiration is a chemical reaction carried out in all living organisms

energy is released from glucose and results in the production of co2 and water

energy is transferred in the form of atp

what is excretion? (mrs gren)

the removal of toxic materials and substances (produced from metabolic reactions) from organisms

what is sensitivity? (mrs gren)

the ability of an organism to detect and respond to stimuli in its surroundings

what is movement? (mrs gren)

an action by an organism causing a change of position or place

what is control? (mrs gren)

ability of living organisms to control their internal environment to keep conditions within required limits (homeostasis)

what is reproduction? (mrs gren)

the process that leads to the production of more of the same kind of organism

what is growth? (mrs gren)

an organism’s ability to permanently increase in size

what are the five kingdoms? which are eukaryotic and which are prokaryotic?

animals

plants

fungi

protoctists

prokaryotes

what are 2 features of eukaryotic organisms?

can be multicellular or single-celled

are made up of cells that contain a nuclear with a distinct membrane

what are 2 features of prokaryotic organisms?

are always single-celled

do not contain a nucleus (instead have nuclear material in the cytoplasm)

what are are 3 features of plants cells?

• cells contain a nucleus with a distinct membrane

• cells have cell walls made out of cellulose

• cells contain chloroplasts

are plants multicellular or single-celled?

multicellular

how do plants feed and store carbohydrates?

plants feed by photosynthesis

they store carbohydrates as starch or sucrose

do plants have nervous coordination?

no

what structures are found in plant cells? what do the plant only structures do?

hint: 5 + 3

cytoplasm

nucleus

mitochondria

ribosomes

cell membrane

vacuole - contains cell sap (solution of sugars + salts dissolved in water); used for storage, helps support shape of the cell

chloroplasts - contain green chlorophyll pigment and enzymes for photosynthesis

cell wall - made of cellulose (polymer of glucose); gives cell extra support

what are 3 features of fungi cells? are they parasitic? do they have nervous coordination?

• cells contain a nucleus with a distinct membrane

• cells have cell walls made of chitin

• cells do not contain chloroplasts

• some are parasitic

• do not have nervous coordination

are fungi single-celled or multicellular?

usually multicellular, but some are single-celled (e.g. yeast)

how do fungi feed and store carbohydrates?

fungi feed by secreting extracellular digestive enzymes onto the food and then absorbing the digested molecules. this is known as saprotophic nutrition

some store carbohydrates as glycogen

what are 3 examples of fungi?

moulds, mushrooms, yeasts

what structures are found in fungi cells? how is a multicellular fungus structured?

hint: 5

nucleus

cytoplasm

ribosomes

cell membrane

cell wall

multicellular fungi are made up of thread-like structures called hyphae that contain many nuclei and are organised into a network known as a mycelium

what are 7 main features of protoctists? what are some examples?

• very diverse kingdom of organisms that don’t belong in any other eukaryotic kingdoms

• mainly microscopic and single-celled but some aggregate into larger forms

• cells contain a nucleus with a distinct membrane

• some have features making them more like animal cells (eg. Plasmodium which causes malaria)

• some have features like cell walls and chloroplasts making them more like plant cells (eg. green algae, Chlorella)

• some protoctists photosynthesise, some feed on other organic substances

• do not have nervous coordination

examples: amoeba, Paramecium, Plasmodium, Chlorella

what are 3 features of prokaryotes? what is an example?

• single-celled

• no nucleus

• nuclear material is found in the cytoplasm

example: bacteria

what are 4 features of bacteria? what do their cells look like? what are some examples?

• microscopic, single-celled organisms

• have a cell wall, cell membrane, cytoplasm, and plasmids

• lack a nucleus but contain circular DNA

• lack mitochondria and have no other membrane-bound organelles

examples: Lactobacillus (rod-shaped and used in the production of yoghurt from milk) and Pneumococcus (spherical and acts as the pathogen causing pneumonia)

how can bacteria feed?

• some carry out photosynthesis without chloroplasts (they possess chlorophyll and the enzymes required)

• most feed on other living or dead organisms

  • if they feed on dead organic matter, they are known as saprobionts or decomposers

components of prokaryotic and eukaryotic cells

Component	Eukaryotes	Prokaryotes
Cell membrane	Y	Y
Cytoplasm	Y	Y
Genetic material	Y - in a nucleus	Y - in the cytoplasm
Nucleus	Y	N
Cell wall	Some types	Y

what is a pathogen? what are some examples?

any microorganism that causes disease in another organism

examples: bacteria, fungi, protoctists, viruses

how do pathogenic bacteria work? what is the bacteria causing TB?

pathogenic bacteria do not always infect the hosts of cells - they can remain within body cavities or spaces

M. tuberculosis causes TB

• bacteria infect the lungs, causing chronic cough and bloody mucus

• often associated with poor hygeine

• M. bovine in cows can transmit to humans to cause TB

what are some examples of pathogenic fungal diseases? where are they most threatening?

cattle ringworm and athletes foot

black sigatoka is a fungal disease in bananas

fungal diseases in plants tend to be much more serious and can threaten entire crops

what is a disease caused by a protoctist? what is the protoctist called?

malaria

Plasmodium falciparum

what are 4 characteristics of viruses?

• they are small particles (smaller than bacteria)

• they are parasitic and can only reproduce inside living cells

• they infect every type of living organism

• they have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA

what are 3 examples of viruses?

TMV (tobacco mosaic virus)

HIV virus, causing AIDS

influenza virus, causing the flu

what is TMV? how is it spread? is there a cure?

TMV was the first virus to be isolated by scientists

it infects tobacco plants and causes distinct mosaic patterns of discolouration on the leaves, and the plants do not grow due to lack of photosynthesis

it is spread by plants being in direct contact with infected plants

no treatment

what is HIV? what are the symptoms? how is it spread? is there a cure?

HIV (Human Immunodeficiency Virus) can eventually lead to AIDS (Acquired Immonodeficiency Syndrome)

starts with a flu-like illness

if untreated it can travel to lymph nodes and attack cells of the immune system

it can stay hidden in the immune system for many years until the immune system is so badly damaged it can no longer deal with other infection or cancers

spread by direct sexual contact

the exchange of bodily fluids

from mother to child during birth or in breast milk

there is no cure

what are the 3 influenza viruses? what are the symptoms of the flu? which virus causes the most infections?

influenza A, influenza B, and influenza C

infects the cells that line the airways

causes a high temperature, body aches, and fatigue

influenza A is the virus that causes the most cases of flu