Unit 1 - 2
Water can stick to other water molecules because of this property.
What is Cohesion?
This organelle is known as the “powerhouse of the cell.”
What is the Mitochondrion?
Gregor Mendel used this plant in his famous heredity experiments.
What is the pea plant?
DNA is transcribed into this type of RNA before leaving the nucleus.
What is mRNA?
Organisms best suited to survive in their environment are more likely to reproduce. This process is called ________.
What is Natural Selection?
A scientist places a red blood cell into pure water. Describe what happens to the cell and why.
The cell swells and may burst because water enters by osmosis in a hypotonic environment.
At the end of the ETC, when oxygen is not present, lactaid acid is made directly from pyruvate. What is this cell undergoing?
What is Lactic Acid Fermentation?
If two heterozygous parents (Aa × Aa) have offspring, what is the probability of producing a recessive offspring?
What is 25% or 1/4?
This molecule carries amino acids to the ribosome during translation.
What is tRNA?
In a food chain, what type of organism is usually found at the very beginning?
What is a producer/autotroph?
A phospholipid has a hydrophilic head and hydrophobic tails. Explain why this structure is important for cell membranes.
It allows membranes to form bilayers with selective permeability, separating internal and external environments.
If the active site of an enzyme changes shape due to high temperature, what happens to the reaction rate and why?
The rate decreases because the substrate no longer fits properly.
A woman who is a carrier for an X-linked recessive disorder has children with a male who does not have the disorder. Why are sons more likely than daughters to express the disorder?
Sons only inherit one X chromosome, so one recessive allele causes expression.
A mutation changes one nucleotide but does not change the amino acid sequence. What type of mutation is this?
What is a Silent Mutation?
A drought causes only plants with deeper roots to survive and reproduce. What type of selection is occurring?
What is directional selection?
Explain why unsaturated fats generally increase membrane fluidity more than saturated fats.
Double bonds create bends that prevent phospholipids from packing tightly together.
A poison prevents hydrogen ions from flowing through ATP synthase. Predict the effect on ATP production.
ATP production would dramatically decrease because chemiosmosis cannot occur.
In pea plants, purple flowers are dominant over white flowers. If 75% of offspring show purple flowers, what is the most likely parental cross?
What is Pp × Pp?
Why can liver cells and muscle cells contain identical DNA but produce different proteins?
Different genes are expressed in different cell types.
After a natural disaster, a population becomes much smaller and loses genetic diversity. What evolutionary effect most likely occurred?
What is the bottleneck effect?
A researcher lowers the pH inside a cell from 7 to 2 and observes proteins losing function. Explain the molecular reason for this loss of function.
The acidic conditions disrupt hydrogen and ionic bonds, altering protein structure.
During intense exercise, muscle cells temporarily switch from aerobic respiration to fermentation. Explain one disadvantage of this shift.
Disadvantage: much less ATP is produced and lactic acid accumulates.
This occurs because a small isolated population carries different allele frequencies purely by chance.
What is the Founder Effect?
A mutation inserts one nucleotide near the beginning of a coding sequence. Why is this usually more harmful than replacing a single nucleotide?
It causes a frameshift mutation that changes many downstream codons.
Antibiotics did not create the mutations; resistant mutations already existed randomly and were selected for over generations.
Why don’t antibiotics directly cause bacteria to evolve resistance?