Biology midterm potential FRQs

Specialization

Cells evolve to perform specific functions, increasing efficiency in multicellular organisms

Compartmentalization

Use of membrane-bound organelles to isolate cellular processes, increasing efficiency.

Prokaryote

Unicellular organism lacking nucleus and membrane-bound organelles.

Eukaryote

Organism with nucleus and membrane-bound organelles.

Unicellular vs Colonial vs Multicellular

One cell / independent cluster of similar cells / many interdependent, specialized cells.

Explain endosymbiosis.

Eukaryotic mitochondria and chloroplasts originated when ancestral prokaryotes were engulfed and formed a mutualistic relationship inside a host cell.

How does compartmentalization support specialization?

by having Organelles isolate incompatible reactions, it allows cells to evolve specialized biochemical pathways.

what is the connection between all this: specialization, compartmentalization, endosymbiosis, prokaryote, eukaryote, unicellular, colonial, multicellular

Life began with simple Unicellular organisms, starting with Prokaryotes. A major leap occurred via Endosymbiosis, leading to the more complex Eukaryotes, whose structure is defined by internal Compartmentalization (organelles). Eukaryotes then formed aggregates, progressing through Colonial stages, eventually evolving into truly Multicellular organisms. This final, complex state is defined by the high degree of cellular Specialization required for coordinated function.

what is oxygen’s role in cell respiration

final electron acceptor in ETC, forms water

what are the 3 similarities between aerobic and anaerobic respiration in animal tissues

primary goal is to make ATP, both use glucose as initial fuel source, both begin with glycolysis

what is the oxygen requirement difference between aerobic and anaerobic respiration

aerobic respiration requires oxygen as the final electron acceptor, anaerobic does not

what is the process location difference between aerobic and anaerobic respiration

aerobic has multiple processes from glycolysis in the cytosol, to krebs cycle in mitochondrial matrix, to oxidative phosphorylation in the inner mitochondrial membrane, while anaerobic only does glycolysis and lactate fermentation in the cytosol

what is the atp yield difference (per glucose) between aerobic and anaerobic respiration

aerobic can make up to 32 atp, but anaerobic makes a net 2 atp from glycolysis only

what is the fate of pyruvate difference between aerobic and anaerobic respiration

in aerobic, pyruvate enters the mitochondrian and is completely oxidized to co2 and h2o, while anaerobic keeps pyruvate in the cytosol and converts it to lactate

what is the purpose of final step difference between aerobic and anaerobic respiration

aerobic wants to generate a ton of atp, while anaerobic regenerates nad+ so glycolysis can go again

what is the duration/sustainability difference between aerobic and anaerobic respiration

aerobic is highly efficient and long term, anaerobic is for short term emergencies

what are the byproducts difference between aerobic and anaerobic respiration

aerobic makes carbon dioxide and water, anaerobic makes lactate

what is the independent variable in the resrveratrol experiment: Researchers hypothesize that the plant compound reveratrol improves mitochondrial function.
To test this hypothesis, researchers dissolve reveratrol in dimethyly sulfoxide (DMSO). The solution readily passes through cell membranes. They add resveratrol solution to mammalian muscle cells growing in a nutrient rich solution (culture medium that contains glucose). They measure ATP at several points after the addition of reveratrol sólution and record an increase in ATP production by the muscle cells.

resveratrol

what is the dependent variable in the resveratrol experiment: Researchers hypothesize that the plant compound reveratrol improves mitochondrial function.
To test this hypothesis, researchers dissolve reveratrol in dimethyly sulfoxide (DMSO). The solution readily passes through cell membranes. They add resveratrol solution to mammalian muscle cells growing in a nutrient rich solution (culture medium that contains glucose). They measure ATP at several points after the addition of reveratrol sólution and record an increase in ATP production by the muscle cells.

ATP production

in the resveratrol experiment, describe a control group they should use: Researchers hypothesize that the plant compound reveratrol improves mitochondrial function.
To test this hypothesis, researchers dissolve reveratrol in dimethyly sulfoxide (DMSO). The solution readily passes through cell membranes. They add resveratrol solution to mammalian muscle cells growing in a nutrient rich solution (culture medium that contains glucose). They measure ATP at several points after the addition of reveratrol sólution and record an increase in ATP production by the muscle cells.

use a DMSO only control group

Predict ATP production with resveratrol but no glucose.

ATP decreases because glucose is required for glycolysis and as a substrate for mitochondrial respiration.

if glucose is not limiting during the resveratrol experiment, Why would O₂ consumption increase? Researchers hypothesize that the plant compound reveratrol improves mitochondrial function.
To test this hypothesis, researchers dissolve reveratrol in dimethyly sulfoxide (DMSO). The solution readily passes through cell membranes. They add resveratrol solution to mammalian muscle cells growing in a nutrient rich solution (culture medium that contains glucose). They measure ATP at several points after the addition of reveratrol sólution and record an increase in ATP production by the muscle cells. The researchers find that reveratrol appears to stimulate aspects of the electron transport chain.
The researchers predict that resveratrol treatment will increase oxygen consumption by the cells if glucose is not limiting. Provide a justification for the researcher's claim.

Stimulating ETC increases electron flow; more O₂ is required as the final electron acceptor.

Main trigger for breathing rate

increased carbon dioxide, which lowers blood pH.

Where CO₂ is mostly carried

Bicarbonate ions (HCO₃⁻).

Respiratory control center

Medulla oblongata.

Connection between CO₂, pH, hemoglobin.

Higher CO₂ lowers pH, shifting hemoglobin right (Bohr shift), increasing O₂ unloading to tissues.

Where would PDC be most active? The pyruvate dehydrogenase complex (PDC) catalyzes the conversion of pyruvate to Acetyl-CoA, a substrate for the Krebs (citric acid) cycle. Thę rate of pyruvate conversion is greatly reduced in individuals with PDC deficiency, a rare disorder.

mitochodrial matrix

Effect of PDC deficiency on NADH.

Krebs cycle NADH decreases due to less acetyl-CoA; glycolysis NADH unaffected.

effect on ATP from ETC

lower NADH and fadh2 reduce electron flow, lowering production

where does glycolysis occur

cytosol

what 3 things does glycolysis produce

2 pyruvate, 2 net atp, 2 nadh

what 3 things does pyruvate oxidation produce

acetyl-coa, nadh, co2

where does pyruvate oxidation and krebs cycle occur

mitochondrial matrix

what 4 things does krebs cycle make

nadh, fadh2, co2, atp

what is the role of the proton gradient in ETC/oxidative phosphorylation

it drives atp synthase

what do glycolysis and pyruvate oxidation contribute to atp synthesis (what do they do to the glucose, and what two other things do they produce)

They break down glucose into pyruvate and then Acetyl-CoA, producing a small amount of ATP and generating NADH, which carries high-energy electrons to the ETC for major ATP production.

what 3 things does krebs cycle contribute to atp synthesis

oxidizes Acetyl-CoA

produces large amounts of NADH and FADH₂,( the electron carriers that fuel the ETC)

makes small amount of ATP directly through substrate-level phosphorylation.

What is the contribution of the electron transport chain (ETC) to ATP synthesis?

The ETC uses electrons from NADH and FADH₂ to pump H⁺ ions across the inner mitochondrial membrane, creating a proton gradient that drives ATP synthase to produce most of the cell’s ATP through oxidative phosphorylation.

How does the fact that nearly all existing organisms perform glycolysis support the claim that glycolysis evolved in a common ancestor?

Because glycolysis is shared across bacteria, archaea, and eukaryotes, the most logical explanation is that the pathway originated before these lineages diverged, meaning it was present in the earliest common ancestor of all life.

How does the fact that glycolysis occurs under anaerobic conditions support early evolutionary origins?

Early Earth had little to no oxygen, so organisms needed a metabolic pathway that worked without oxygen. Glycolysis fits this requirement, suggesting it evolved in ancient, anaerobic environments and was passed down to all later life forms.

How does the fact that glycolysis occurs only in the cytosol support its presence in a common ancestor?

The cytosol is the simplest, most primitive cell compartment. Because glycolysis does not require specialized organelles or membranes, it likely evolved before complex cell structures existed, indicating it originated in the earliest cells.

what happens to the excess energy from glucose metaboism that is not captured in ATP?

released as heat to help maintain body temp or lose to environment

why is cellular respiration not 100% efficient

because energy is lost as heat during metabolic reactions and electron transport, and some energy is unavailable because of thermodynamic limits

the enzymes for the krebs are found in the ctyoplasm of bacteria, but in the mitochondria of eukaryotes. briefly explain this evolutioanry connection

bacteria perform krebs in cytoplasm because they lack membrane bound organelles. eukaryotes perform it in mitochnodria because mitohoncdria evolved from ancestral bacteria through endosymbiosis, and their metabolic pathways including krebs became localized inside the mitochondrion

descibre how the lock and key model for enzyme action explains the ability of enzymes to catayze either hydroylsis or dehydration syntehesis reactions

in the model the enzyme’s active site fits the substrate exactly. because of that correct orientation, the enzme can either stress and weaken bonds or hold two substrates together, the specific shape ensuring only the correct reaction occurs with the correct substrate

why doe enzymes have different ph optima

ph affects the ionic interactions that stabilize an enzyme’s shape and active site, so each enzyme works best at a specific ph

give an example of an enzyme starting with a p adapted to acidic ph

pepsin, which works best in stomach at abotu ph 2

give an example of an enzyme adapted to neutral ph starting with a c

chymotrypsin, which functions in the small intestine at ph 7

how do ph and temp. differences relate to orgnaism distribution

different organisms and tissues evolve enzymes sutied to their environments, allowing survival in acidic, neutral, basic, hot, or cold conditions

they show that metabolic rate is tied to temperature regulation, as endotherms use metabolism to maintain internal temperature, and smaller animals burn more energy to resist heat loss

how would temperatures above 35 celsius impact the structure and function of starch synthase specifically

the active site partially unfolds, lowering enyzme activity and slwoing or preventing the ocnversion of glucose into starch

what digestion begins in the mouth?

carb digestion through salivary amylase which breaks starch into maltose

what process moves food thorugh the esophagus

peristalsis, wavelike muscle contractions

what molecuels are digested in the stomach and by which enzyme

proteins are digested by pepsin

what stomach conditions activate pepsin

highly acidic ph of 2

what structural adpatation helps stomach digestiong

folds increase surface area and allow expansion

where does most chemical digestion occur

duodenum of small intestine

what 4 things are digested in small intestine

carbs, proteins, lipids, nucleic acids

what enzymes come from the pancreas

trypsin, chymotrypsin, pancreatic amylase, lipase, nucleases

what does bile do

breaks large fat globules into smallero nes

what structural adaptation increases absoprtion in the small intestine

villi and microvilli create massive surface area

how are nutrients absorbed in small intestine

through active transport, diffusion or co transport into blood or lymph for fats

main function of large intestine?

water absorption and the formation of feces

role of liver in digestion

makes bile and processes absorbed nutrients

role of gallbladder in digetsion?

stores and concentrates bile

role of pancreas in digestion?

makes digestive enzymes and bicarbonate to neutralize stomach acid

what is the correct order of digestion from ingestion to elimination MESSLRA

mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

why do herbivores have logner digestive tracts

plant material like cellulose is harder to digest

where and how are carbs digested (2 places, two enzymes)

the mouth by salivary amylase and the small intestine by pancreatic amylase

where and how are proteins digested (2 places, 4 ways total)

in the stomach by pepsin, the small intestine by trypsin, chymotrypsin, and peptidases

where and how are lipids digested

in small intestine by bile

where and how are nucleic acids digested

in small intestine by nucleases from pancreas

why is the stomach acidic?

the acid denatures proteins and activates pepsinogen to pepsin

why do villli help with absorption

they drastically increase surface area, maximizing nutrient uptake