1) Nature and Variety of living organisms

Question 1

Characteristics of living organisms

Answer 1

MRS GREN
-movement
-respiration
-sensitivity
-growth
-reproduction
-excretion
-nutrition

Question 2

Living organism classification

Answer 2

Eukaryotes:
-animals
-fungi
-plants
-protoctists
Prokaryote:
-bacteria

Question 3

Plants

Answer 3

-multicellular
-contain chloroplasts and carry out photosynthesis
-convert simple organic molecules water and carbon
-into complex organic compounds:
–cellulose - cell walls
–starch - transported around the plant and sometimes storedin fruits, other plant organs

Question 4

Animals - vertebrates/ invertebrates

Answer 4

-vertebrates (have a backbone): fish, amphibians, reptiles, birds, mammals
-invertebrates (no backbone): sponges molluscs, worms, starfish, insects

Question 5

Animals

Answer 5

-multicellular
-never contain chloroplasts
-gain nutrition by feeding on other animals/ plants
-store carbohydrate in their cells as glycogen

Question 6

Animals - movement

Answer 6

-lack cell walls - allow cells to change shape - organisms can move from place to place
-often involves coordination by a nervous system

Question 7

Fungi

Answer 7

-multicellular - mushrooms, toadstools, moulds
-unicellular - yeasts
-cannot photsynthesise
-cell walls made of chitin

Question 8

Structure of fungi

Answer 8

-fruiting body/ reproductive structure: mushroom/ toadstool
-hyphae: fine thread like filaments called hyphae under the soil

Question 9

Fungi - mould

Answer 9

Mushroom without the fruiting body
-consists of the network of hyphae
-whole network - mycelium
-feed by absorbing nutrients from the dead material

Question 10

Fungi - mucor

Answer 10

-hyphae of mucor have cell walls surrounding their cytoplasm
-cytoplasm contains many nuclei - hyphae are not divided up into separate cells

Question 11

How mold grows on food

Answer 11

-spore from mucor lands, hypha grows out from it
-grows and branches again and again until the mycelium covers the surface of the food
-hyphae secrete digestive enzymes onto the food
-breaks it down into soluble substances such as sugars - absorbed by the mould
-eventually food is used up
-mould must infect another source by producing more spores

Question 12

Saprotrophic nutrition

Answer 12

When an organism feeds on dead organic material and digestion takes place outside of the organism
-extracellular enzymes: enzymes secreted out of cells for this purpose

Question 13

Protoctists

Answer 13

-mixed group of organisms, don’t fit in others
-amoeba, like animal cells - lives in pond water
-chlorella - have chloroplasts
-plasmodium - causes malaria

Question 14

Eukaryotic organisms

Answer 14

Have organelles within cell
-Basis for unicellular, multicellular

Question 15

Prokaryotic cells

Answer 15

No organelles
-only for unicellular

Question 16

Bacteria

Answer 16

-small, single celled organisms
-cells are much smaller than eukaryotic organisms
-basic shapes: spheres, rods, spirals
-many are important decomposers
-used by humans to make food - lactobacillus bulgaricus
-some are pathogens - cause disease

Question 17

Bacteria structure

Answer 17

-Cell wall
-Capsule/ slime layer
-Cell membrane
-Cytoplasm
-No nucleus (prokaryotic cell)
-chromosome (nucleoid)
-Flagella
-plasmid
-some have chlorophyll

Question 18

Bacteria - cell wall

Answer 18

-protects bacterium/ keeps shape of the cell
-made of a complex compound of sugars and proteins - peptidoglycan

Question 19

Bacteria - capsule/ slime layer

Answer 19

-another layer outside cell wall
-give extra protection

Question 20

Bacteria - chromosome

Answer 20

-genetic material in a single chromosome
-loose in the cytoplasm
-form a circular loop

Question 21

Bacteria - flagella

Answer 21

-some bacteria can swim, propelled through water by corkscrew-like movements of flagella
-don’t have flagella, can’t move

Question 22

Bacteria - plasmid

Answer 22

-small circular rings of DNA
-carry some of bacterium’s genes

Question 23

Viruses

Answer 23

-smaller than bacteria
-parasitic and can reproduce only inside living cells
-infect every type of living organism
-wide variety of shapes and sizes
-no cellular structure
-have a protein coat and contain either DNA or RNA

Question 24

Viruses - as a parasite

Answer 24

-envelope stolen from surface membrane of host cell may surround a virus particle
-infect plant cells - e.g. tobacco mosaic virus interferes with the ability of the tobacco plant to make chloroplasts - cause mottled patches to develop

Question 25

Viruses - reproduction

Answer 25

-virus reproduces by entering the host cell, takes over the host’s genetic machinery to make more virus particles
-after many virus particles have been made, the host cell dies
-particles are released to infect more cells

Question 26

Viruses - diseases

Answer 26

-e.g. influenza, colds, measles, mumps, polio
-usually the body’s immune system destroys the virus and the person recovers
-if it is not destroyed quickly enough - may cause permanent damage/ death
-virus may attack cells of the immune system - e.g. HIV causes AIDS