EL lect 1-6

Question 1

• Define anaerobic

Answer 1

living, active, occurring/ existing in the absence of oxygen

Question 2

• Define cyanobacteria

Answer 2

group of photosynthetic bacteria that obtain energy via photosynthesis

Question 3

• Define properties

Answer 3

characteristics that give each substance a unique identity

Question 4

• Define processes

Answer 4

a method or event that results in a transformation of a physical or biological object eg change of physical state

Question 5

• What are the 6 characteristics of living organisms?

Answer 5

• Growth and development
• Reproduction (including the transmission of genetic information)
• Response to the environment
• Evolutionary adaptation
• Energy processing (metabolic processes)
• Regulation (homeostasis)

Question 6

• Why are viruses not living organisms?

Answer 6

They don’t grow, and they can’t make their own energy.

-They are ‘replicators’ since they do not metabolise

Question 7

• What are the 3 domains?

Answer 7

• Archaea
• Bacteria
• Eukaryota

Question 8

• What are the 5 kingdoms and describe them?

Answer 8

1) Plantae
eukaryotic, multicellular, obtain food from photosynthesis,sexual

2) Fungi
eukaryotic, multicellular, absorbs nutrients from outside their bodies,sexual

3)Protists
unicellular eukaryotes, absorb/ingest/photosynthesise nutrients, sexual and asexual

4) Animalia
multicellular eukaryotes, ingest other organisms, sexual

5) Bacteria
unicellular prokaryote, absorb/photosynthesise, asexual

Question 9

• Define multicellular and unicellular

Answer 9

• multicellular= tissue, organ/organism made up of many cells, often there is specialization of different cells for various functions
• unicellular= single-celled organism

Question 10

• Define eukaryote and prokaryote

Answer 10

• eukaryote= organisms whole cells have a mucleus enclosed by a nucleur envelope.
• Prokaryotes= cellular organism that lacks an envelope-enclosed nucleus

Question 11

• Explain the primordial soup theory

Answer 11

• early earth constantly bombarded by rocks and meteorites
• Bombardment vaporised water and prevented it from condensing to form seas until 4 bil years ago
• before life, there was very little oxygen in atmosphere, it had water vapour and a lot of chemicals were released by volcanic eruptions
• earth began to cool as volcanic activity slowed and water vapour in atmosphere eventually condensed to form oceans
• as water condensed and formed oceans, we ended up with oceans that contained all chemicals found in air and that was our primordial soup.
• so the ocean contained all substances needed for life to exist, it just needed to come together
• it is believed that the coming together happened by using energy from UV radiation/ lightning

Question 12

• What was the oparin-Haldane hypothesis?

Answer 12

The Oparin-Haldane hypothesis suggests that life arose gradually from inorganic molecules, with “building blocks” like amino acids forming first and then combining to make complex polymers.

Question 13

• Explain the miller experiment

Answer 13

-scientist miller attempted to stimulate earth’s early atmosphere to see if they could make these organic molecules in the presence of H2O vapour and electric energy

Question 14

• Explain the meteorite theory and state the name of the famous meteorite

Answer 14

• Theory suggests that organic molecules needed to form life on earth came from meteorites
• Murchision meteorite= contained a lot of organic material

Question 15

• Explain the hydrothermal vent theory

Answer 15

• suggests that origin of life was found on deep sea hydrothermal vents
• Geological structures found on the sea floor were produced through chemical reactions that occur between sea water and fluids that are ejected from the earths crust
• these vents have all of the chemicals and energy that was needed for many of the reactions to take place for life to evolve
• alkaline fluid hits the more acidic sea water and creates a proton gradient, this proton gradient was able to drive chemical reactions in primitive cells that formed
• cells developed at these vents relied on the proton gradient set up and over time they evolved to be able to set up their own proton gradient
• once they did they could move away from the vents and colonise other areas of the ocean.

Question 16

• What is a protocell and how did they form?

Answer 16

• Precursors to early life

- small organic molecules joined up to form polymers which got packaged to form protobionts.

Question 17

• How do they look?

Answer 17

Microspheres of organic and inorganic molecules inside a lipid bilayer
-tiny droplets of molecules surrounded by a membrane

Question 18

• What’s the other name for protocell?

Answer 18

Protobionts

Question 19

• Why weren’t they truly alive?

Answer 19

They didn’t have RNA and DNA

Question 20

• What are the 4 characteristics of all cells?

Answer 20

• Are enclosed by a plasma membrane
• Have cytoplasm in which other cell components are
• found Have genetic material
• Mitosis - clonal reproduction of cells
• Meiosis cell division forming modified cells

Question 21

• Explain the differences between prokaryotic and eukaryotic cells

Answer 21

• Prokaryotes have a circular chromosome while eukaryotes have chromosomes enclosed in a double membrane
• P have no membrane bound organelles and E have membrane bound organelles
• P has small sized cells and E has larger cells

Question 22

• Explain autogenesis hypothesis

Answer 22

• ancestral prokaryotic cells grew and as it grew in size ,it caused a low SA to V ratio so it wasnt able to absorb enough nutrients/chemicals from its environment
• so infolding of membrane took place and then the infolding pinched off from the cell membrane, those infolds held within the cell went on to form ER, nuclear envelope and golgi apparatus
• however this does not provide evidence for other organelles such as mitochondria and chloroplast.

Question 23

• Explain endosymbiosis hypothesis

Answer 23

• An ancestral cell took in prokaryotes as food however instead of digesting them they stayed as symbionts

Question 24

Explain serial endosymbiosis

Answer 24

• An Anaerobic ancestral eukaryote cell absorbed an aerobic heterotrophic prokaryote/ was a parasite to the host cell
• instead of digesting the cell it formed a symbiotic relationship because the aerobic quality of the prokaryote was an advantage in the environment with increasing oxygen
• over time the two cells became dependant on each other as the eukaryote provided a safe environment and the prokaryote provided energy so the prokaryote became mitochondria and they started functioning as a single unit
• some primitive eukaryotes absorbed more symbionts in the form of photosynthetic prokaryotes as they needed them to allow for photosynthesis to take place
• eventually they too became dependent on each other so the chloroplast was assimilated into the cell and formed plastid.
• eventually they lost their cell wall and much of their DNA that wasn’t useful for the host cell.

Question 25

provide the evidence for endosymbiosis

Answer 25

Mitochondria, Chloroplast and bacteria are:

• similar in size
• have their own double circular strand of DNA
• double membrane
• own ribosomes
• reproduce via binary fission

Question 26

• What are symbionts?

Answer 26

organism living in a symbiotic relationship with another organism.

Question 27

• What is a heterotroph?

Answer 27

organism that cannot produce its own food, takes nutrition from other sources or organic carbon

Question 28

• What is an autotroph?

Answer 28

an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

Question 29

• What is a plastid?

Answer 29

membrane bound organelle found in plants, algae and some other eukaryotic organisms eg chloroplasts, chromoplasts …

Question 30

• Give me the summary of endosymbiosis and autogenesis in a 5 step process

Answer 30

1- Prokaryote grows in size and develops infoldings in CSM to increase SA:V ratio
2-Infoldings eventually pinch off from CSM forming endomembrane system
3- aerobic prokaryote enters ancestral eukaryote and forms endosymbiotic relationship
4- Aerobes ability to make energy using O2 becomes an asses allowing host to thrive in the increasing O2 environment. Prokaryote is assimilated and becomes mitochondrion
5- Some primitive eukaryotes go to equire additional endosymbionts- the cyanobacteria (capable of photosynthesis)