The nature and variety of living organisms

Question 1

​MRS C GREN=

Answer 1

Movement​: can change position
Reproduction​: can have offspring either sexually or asexually
Sensitivity​: can detect stimuli, such as light, and respond to them
Control​: can control their internal environment (homeostasis)
Growth​: can increase mass
Respiration​: can produce energy either aerobically or anaerobically
Excretion​: can remove toxic or waste produced produced by reactions in the body Nutrition​: can absorb nutrients in order to use them for growth and repair

Question 2

eukaryotic-Plants=

Answer 2

● E.g. cereals (such as maize) or herbaceous legume (such as peas)
● Multicellular​ organisms
● Cells contain ​chloroplasts ​which is the site of ​photosynthesis​: ​chlorophyll​ pigments within the

chloroplast structure absorb light from the Sun
● Cellulose​ cell walls which provide strength to the cel
l● Contain a ​permanent vacuole​, which stores cell sap and improves the cell’s rigidity
● Store carbohydrates as ​starch or sucrose

Question 3

eukaryotic- animals=

Answer 3

● E.g. mammals (such as humans) and insects (such as flies)
● Multicellular
● Cannot photosynthesise
● Do not have cell walls
● Have ​nervous systems​ in order to coordinate movement
● Store carbohydrates as ​glycogen

Question 4

eukaryotic- fungi=

Answer 4

● Body is usually organised into a ​mycelium​ of thread-like structures called ​hyphae​ which have many nuclei ​but some are ​single-celled
● E.g. ​Mucor ​has typical hyphal structure, yeast is single-celled
● Cell walls are made of ​chitin
● Feed by extracellular secretion of digestive enzymes which break it down into smaller pieces,
which can then be absorbed (​saprotrophic nutrition​)
● May store carbohydrates as ​glycogen

Question 5

eukaryotic- protoctists=

Answer 5

● Single-celled​ organisms
● Some have features​ like animals cells​, such as ​Amoeba​, that live in pond water
● Others are more​ like plants​ and have chloroplasts, such as ​Chlorella

Question 6

prokaryotes- bacteria=

Answer 6

● E.g. Lactobacillus bulgaris (rod-shaped bacterium used to make yoghurt), Pneumococcus (spherical bacterium that causes pneumonia)
● Single-celled​ and very small
● Have a​ cell wall, cell membrane, cytoplasm and plasmids
● Lack a nucleus ​but have​ circular chromosomes​ of DNA
● Some can carry out photosynthesis but they mainly eat off of other organisms, either dead or
alive

Question 7

pathogens- viruses=

Answer 7

● E.g. tobacco mosaic virus which prevents chloroplast formation, influenza virus, HIV virus leading to AIDS
Pathogens (1.4)
● Viruses are small particles (much smaller than bacteria) - ​not living organisms
● Parasitic
○ Can only reproduce within living cells
○ Can infect every type of living organisms
○ Hijacks the cell mechanisms to create millions of copies of itself and then spreads
within the host by cell bursting
● They come in a wide variety of shapes and sizes
● Do not have a cellular structure but have one type of​ nucleic acid​ (either DNA or RNA) and a
protein coat

Question 8

pathogens- bacteria=

Answer 8

● E.g. Salmonella (food poisoning)
● Can reproduce many times through ​binary fission
● Produce toxins that can damage cells

Question 9

pathogens- protists=

Answer 9

● E.g. malaria
● Parasitic ​- use animals as their hosts to live in

Question 10

pathogens- fungi=

Answer 10

● E.g. Athlete’s foot
● Produce ​spores​ that can spread in the wind or between people
● Can treat with ​fungicides