UPCAT Biology Review Flashcards

A comprehensive set of practice questions covering the UPCAT Biology review transcript, including cellular biology, genetics, evolution, and human anatomy.

What is the definition of homeostasis?

The maintenance of a steady internal state despite external changes.

Which part of the brain acts as the physiological thermostat to detect temperature?

The hypothalamus.

What is the difference between endothermic and ectothermic heat sources?

Endothermic organisms rely on internal metabolism for heat, while ectothermic organisms rely on the external environment (sunlight, warm surfaces).

What process joins monomers into polymers by removing water?

Dehydration synthesis.

What process breaks polymers back into monomers by adding water?

Hydrolysis.

Identify the monomers for the four major classes of macromolecules.

Proteins: amino acids; Lipids: fatty acids + glycerol; Carbohydrates: monosaccharides; Nucleic Acids: nucleotides.

What are the two monosaccharides that form sucrose?

Glucose + fructose.

What are the primary storage polysaccharides in plants and animals?

Plants: starch; Animals: glycogen.

How do insulin and glucagon regulate blood sugar?

Insulin promotes glucose uptake and glycogen synthesis when blood glucose is high; Glucagon stimulates glycogen breakdown to release glucose when blood glucose is low.

What represents the 'Fluid Mosaic Model' of the plasma membrane?

A bilayer with hydrophobic tails inward and hydrophilic heads outward, containing proteins, carbohydrates, and cholesterol.

What is the function of the nucleolus?

It is the site of ribosomal RNA ($rRNA$) synthesis and ribosome production.

Which organelle is responsible for lipid and steroid synthesis?

Smooth ER (Endoplasmic Reticulum).

What role do lysosomes play in the cell?

Digestion and recycling by releasing acid hydrolases to degrade old organelles or pathogens.

What is the primary function of peroxisomes?

To detoxify reactive oxygen species (ROS) such as hydrogen peroxide ($H_2O_2$) using enzymes like catalase and peroxidase.

How does the state of turgor pressure differ between turgid and flaccid plant cells?

In a turgid state, water enters the central vacuole and presses the membrane against the cell wall; in a flaccid (plasmolyzed) state, water is lacking and the cell loses rigidity.

What is the main difference between passive and active transport?

Passive transport requires no ATP and moves substances from high to low concentration; active transport requires ATP and moves substances against their concentration gradient (low to high).

Explain the action of the primary active transport pump $Na^+/K^+-ATPase$.

It moves $3Na^+$ out of the cell and $2K^+$ into the cell using ATP.

What are the three sub-phases of interphase and their main events?

$G_1$ (cell growth), $S$ (DNA replication), and $G_2$ (preparation for mitosis and DNA checks).

Compare the resulting product cells of mitosis and meiosis.

Mitosis produces 2 identical diploid cells; Meiosis produces 4 non-identical haploid cells.

Name the four key enzymes involved in DNA replication and their functions.

Helicase (unwinds helix), Primase (synthesizes RNA primer), DNA polymerase (adds nucleotides), and DNA ligase (seals gaps).

What are the start and stop codons in translation?

Start: $AUG$ (Methionine); Stop: $UAA$, $UAG$, $UGA$.

In a Punnett square for blood type, what is the probability of a type A child if the father is heterozygous type A ($I^A i$) and the mother is homozygous type B ($I^B I^B$)?

$0$ (The offspring would be 50% type AB and 50% type B).

Why do males (XY) express X-linked recessive traits more frequently than females?

They inherit a single X chromosome, so there is no second X chromosome to mask a mutant allele.

Define 'Fitness' in the context of natural selection.

The ability of an organism to survive and reproduce in its environment.

What is the difference between microevolution and macroevolution?

Microevolution involves small-scale changes in allele frequency within a population; macroevolution involves large-scale changes such as speciation.

List the six kingdoms in the modern classification model.

Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia.

Where do the three stages of cellular respiration occur?

Glycolysis: cytosol; Krebs Cycle: mitochondrial matrix; Electron-Transport Chain: inner mitochondrial membrane.

What is the '10% rule' in ecological energy transfer?

Only approximately $10/$ of energy is transferred from one trophic level to the next.

Identify the four primary tissue types in animals.

Epithelial, Connective, Muscle, and Nervous.

Contrast the functions of ligaments and tendons.

Ligaments connect bone-to-bone; tendons connect muscle-to-bone.