Bio Concept 1 practice questions Flashcards
Why are information transmission, energy transfer, and evolution considered basic to life?
Organisms must be able to send and receive information within their own bodies and with other organisms in their environment.
Must be able to transform energy from one form to another to perform life functions
Must evolve or change as their environment changes.
What would be the consequences to an organism if its homeostatic mechanisms failed? Explain your answer
Could not maintain metabolic processes and would die.
In what ways does evolution depend on transfer of information? In what ways does transfer of information depend on evolution?
Evolution depends on information transfer = organisms must be able to respond to changes in their environment for the population to adapt.
Info transfer depends on evolution = as an organism adapts to the environment, communication may change.
A typical prokaryotic cell has about 3,000 genes in its DNA, while a human cell has about 21,300 genes. About 1,000 of these genes are present in both types of cells. Explain how such different organisms could have this same subset of 1,000 genes. What sorts of functions might these shared genes have?
All life was initially single-cell organisms that evolved over time (conserved during the evolution of different groups including evolution of eukaryotic cells from a shared ancestor). As all life has a single origin, these 1,000 common genes between prokaryotes and human cells showcase the common ancestors shared by both cell types. The functions of these shared genes would likely relate to prokaryotic cell function, and may even be redundant in human cells (housekeeping genes, like transcription and translation)
Describe electronegativity and how it affects interactions between water molecules.
Electronegativity = attraction of an atom for electrons of a covalent bond.
Oxygen more electronegative than hydrogen so pulls electrons towards itself = 2 partial negative charges for oxygen & a partial positive for each hydrogen.
Atoms in neighboring water with opposite partial charges = hydrogen bond
What would be the effect on the properties of the water molecule if oxygen and hydrogen had equal electronegativity?
The molecule would not be considered polar, and therefore be unable to attract other water molecules, or other molecules, so adhesion and cohesion would not occur.
+ not form hydrogen bonds
No partial charges
Explain why the central water molecule can hydrogen-bond to other water molecules.
Water is a polar molecule. Hydrogen bond forms between partially negatively charged region on the oxygen and the partially positive hydrogen of a nearby water molecule. Basis for water’s properties.
What properties does silicon share with carbon that would make silicon-based life more likely than, say, neon-based life or aluminum-based life?
Silicon is atomic no. 14.
This means 4 unpaired electrons (like carbon)
This means it could also form 4 covalent bonds (like carbon).
Has atomic mass less than 21 (property of elements known to participate in formation of biologically important molecules).
Silicon more prevalent on earth than carbon.
Silicon dioxide in cell walls of plants and diatoms but silicon based life has not been identified.
Because there is so much silicon on Earth, yet no silicon based life, there must be something within this atom’s formation of molecules that makes it impossible for it to make living organisms.
When table salt (sodium chloride, NaCl) is added to water, it breaks apart into sodium ions and chloride ions as it dissolves. When sugar (sucrose, C12H22O11) is added to water, it does not break into smaller pieces as it dissolves. How can you explain this difference in behavior?
Salt – water molecules cluster around Na+ (o side facing them) and Cl – ions (H side facing) in ionic lattice.
This pulls individual ions out of the lattice and surrounding them.
Ionic bonds are disrupted, and individual charged atoms can move apart.
Sugar – lattice of sucrose molecules (as opposed to charged ions) and held together by intermolecular forces (hydrogen bonding).
Water forms new hydrogen bonds with sucrose molecules (specifically -OH group on sugar molecules).
This pulls them out of lattice & disrupting intermolecular attractions with each other.
No atom-atom bonds (like ionic, covalent) are broken or disrupted.
Instead, weaker intermolecular forces are disrupted.
