IB BIO TOPIC 2.1 : CELLS Flashcards
What organisms are considered acellular ?
Unicellular organisms
Viruses
What are the 4 outlines of cell theory ?
- ) living organisms are composed of cells
- ) Cells are the smallest unit of life
- ) Cells come from pre-existing cells
- ) Cells are units if structure and function
What makes a hypothesis become a theory ?
Accumulation if evidence
A theory can be : … Or ….
Rejected or adapted
As evidence is accumulated theories need to be :
Reviewed or altered or abandoned
Outline 3 characteristics of the cells :
- )nothing smaller than a cell can survive independently
- ) sub cellular structures cannot live independently (nuclei, Golgi, chloroplast…)
- ) the lower limit on cell size is about 200nm
Outline 4 points on “origin of life”
- ) life always existed is incompatible with geological evidence on age of earth
- ) exception made for origin of life, cells must have arisen from non living substances
- ) condition of early earth are Anaerobic = precluding the formation of cells from non-living substances
State the advantages of Light Microscope
- ) colour images instead of monochromic
- ) easily prepared sample material
- ) possibility to observe living material and movement
- ) larger field of view
State the advantages of Electron Microscopes
- ) higher resolution
- ) more separate particles and clearer picture
- ) Higher magnification to see smaller objects
State the 6 functions of life carried by unicellular organisms :
Metabolism Sensitivity Homeostasis Growth Reproduction Nutrition
Explain Metabolism
Chemical reactions inside the cells , including cell respiration to release energy.
Explain sensitivity
Perceiving and responding to changes in the environment
Explain homeostasis
Keeping conditions inside the organisms within tolerable limits
Explain growth
An irreversible increase in size
Explain reproduction
Producing offspring either sexually or asexually
Explain nutrition
Obtaining Food to provide energy and all the material needed for growth
State the sizes of the following : Molecules Cell membrane Viruses Bacteria Organelles Eukaryotic cells
Molecules : ~1nm Cell membrane : ~ 10nm Viruses : ~ 100nm Bacteria :~ 1um Organelles : up to 10um Eukaryotic cells : up to 100um
What does “um” and “nm “mean ?
And what are their sizes in relation to each other ?
"nm" = nanometer "um" = micrometer
1000nm = 1um 1000um = 1mm
State the sizes of these : Atom Small molecules Lipids Proteins Ribosomes Mitochondrion
Atoms = ~0.1 nm Small molecules =~ less than 1nm Lipids =~ 1-5 nm Proteins =~ 5-10 nm Ribosomes =~ less than 50 nm Mitochondrion =~ 2um
What is the size of most plant and animal cells ?
Between 100um to 10 um
What is the magnification formula ?
Size of image / actual size of specimen
What is surface area to volume ratio in a cell ?
Surface area to volume ratio decreases when VOLUME INCREASES.
Larger the object = smaller the surface area to volume ratio = slower diffusion rate
State 1 characteristic of a unicellular organism :
Must solve all of life’s challenges within the confines of a single cell
State 4 characteristics of Multicellular organisms :
- ) can differentiate into a variety of interdependent cell types
- ) each specialised to carry out a subset of functions
- ) thereby achieving a greater efficiency
- ) through division of labor among a multicellular cooperative
