section 1: The nature and variety of living organisms

Question 1

functions of all living organisms:

Answer 1

M ovement: can change position
R eproduction: can have offspring either sexually or asexually
S ensitivity: can detect stimuli, such as light, and respond to them
C ontrol: can control their internal environment (homeostasis)
G rowth: can increase mass
R espiration: can produce energy either aerobically or anaerobically
E exretion: can remove toxic waste produced, produced by reactions in the body
N utrition: can absorb nutrients in order to use them for growth and repair

Question 2

eukaryotic organisms:

Answer 2

-> eukaryotes are organisms that have a nucleus and organelles that are found within a plasma membrame
-plants
-animals
-fungi
-protoctists

Question 3

plants: characteristics

Answer 3

e.g. cereals (such as maize) or herbaceous legume (such as peas)
-multicellular organisms
-cells contain chlorplasts which is the site of photosynthesis: chlorophyll pigments within the chloroplast structure absorb light from the Sun
-they store carbohydrates as starch or sucrose

Question 4

animals: characteristics

Answer 4

e.g. mammals (such as humans) and insects (such as flies)
-multicellular organsisms
-cannot photosynthesise
-don’t have cell walls
-most have nervous systems in order to coordinate movement
-store carbohydrates as glycogen

Question 5

fungi: characteristics

Answer 5

e.g. yeast (single-celled) and mucor (has the typical hyphal structure)
-some are single-celled
-others have a body organised into a mycelium of thread-like structures called hyphae which have many nuclei
-cell walls are made of chitin
-feed by extracellular secretion of digestive enzymes which break it down into smaller pieced, which can then be absorbed (saprotrophic nutrition)
-may store carbohydrates as glycogen

Question 6

protoctists: characteristics

Answer 6

e.g. amoeba (animal-cell like + live in pond water) and chlorella (plant-cell like)
-they are microscopic and single-celled
-some have features like animal cells
-others are more like plants and have chloroplasts

Question 7

prokaryotic organisms:

Answer 7

-> prokaryotes do not have a nucleus or membrame-bound organelles
-bacteria

Question 8

bacteria: characteristics

Answer 8

e.g. lactobacillus bulgaris (rod-shaped bacterium used to make yoghurt) and pneumococcus (spherical bacterium that causes pneumonia)
-single-celled and very small
-have a cell wall, cell membrame, cytoplasm and plasmids
-lack a nucleus but have circular choromosomes of DNA
-some can carry out photosynthesis but they mainly eat off of other organisms, either dead or alive

Question 9

pathogens:

Answer 9

-> pathogens are disease-causing organisms and can be fungi, bacteria, protoctists or viruses
-viruses

Question 10

viruses characteristics:

Answer 10

e.g. tobacco mosaic virus which prevents chloroplast formation, influenza virus, HIV virus leading to AIDS
-viruses are small particles (much smaller than bacteria)- not living organisms
-they are parasitics -> 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 spreafs 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 11

pathogens: other pathogens

Answer 11

-protoctists: plasmodium that causes malaria
-bacteria: pneumococcus which causes pneumonia
-viruses: influenza virus (which causes the ‘flu’) and HIV (which causes AIDS)
-fungi: causes athlete’s foot but can be treated with fungicides