STEM Readiness: Physics Readiness - Kinematics: Projectile Motion - Independence of Axes, Range, Max Height, Angled Launch

Must?Know (20–25 detailed bullets)

• Prokaryotic cells range from 0.1–5.0 ?m in diameter; eukaryotic cells range from 10–100 ?m.
• Prokaryotes include bacteria and archaea; eukaryotes include animals, plants, fungi, and protists.
• DNA in prokaryotes is located in the nucleoid, a region without a membrane; eukaryotes house DNA within a membrane-bound nucleus.
• Prokaryotes lack membrane-bound organelles; eukaryotes contain organelles such as mitochondria, lysosomes, and the Golgi apparatus.
• Ribosomes in prokaryotes are 70S (composed of 50S and 30S subunits); eukaryotic cytoplasmic ribosomes are 80S (60S and 40S).
• Mitochondria and chloroplasts in eukaryotes contain 70S ribosomes, similar to prokaryotes, supporting the endosymbiotic theory.
• Prokaryotic cell walls typically contain peptidoglycan (e.g., Escherichia coli); archaea lack peptidoglycan but may have pseudopeptidoglycan.
• Plant cell walls are made of cellulose; fungal cell walls contain chitin; animal cells lack cell walls.
• Both prokaryotes and eukaryotes have a phospholipid bilayer plasma membrane that regulates transport.
• Eukaryotes have an endomembrane system including the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and vesicles; prokaryotes do not.
• Mitochondria are the site of aerobic respiration in eukaryotes and have double membranes; prokaryotes perform respiration on the plasma membrane.
• Chloroplasts are found in plant and algal cells, conduct photosynthesis, and have thylakoids and chlorophyll; absent in prokaryotes (except in cyanobacteria, which use thylakoid membranes without organelles).
• Cyanobacteria are prokaryotes that perform oxygenic photosynthesis using infolded membranes, not chloroplasts.
• Nuclear envelope in eukaryotes is double-membraned with nuclear pores that regulate RNA and protein transport; prokaryotes lack this structure.
• Nucleolus within the nucleus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly; absent in prokaryotes.
• Lysosomes in animal cells contain hydrolytic enzymes for digestion; plants and fungi use vacuoles for similar functions.
• Large central vacuole in plant cells maintains turgor pressure and stores ions; absent in most animal cells.
• Centrioles in animal cells assist in microtubule organization during cell division; absent in most plant and fungal cells.
• Mycoplasma species are bacteria without a cell wall, an exception to typical prokaryotic structure.
• Mature mammalian red blood cells lack a nucleus and mitochondria, an exception among eukaryotic cells.
• Endosymbiotic theory is supported by mitochondria and chloroplasts having circular DNA, 70S ribosomes, and the ability to replicate independently of the host cell.
• Flagella in prokaryotes are made of flagellin and rotate; eukaryotic flagella are made of microtubules (9+2 arrangement) and undulate.
• Cilia are short, numerous motile structures in some eukaryotes (e.g., Paramecium); prokaryotes lack cilia.
• Plasmids are small, circular extrachromosomal DNA molecules common in prokaryotes; rare in eukaryotes.
• Eukaryotic cytoskeleton includes microfilaments (actin), intermediate filaments, and microtubules (tubulin); prokaryotes have homologs (e.g., FtsZ) but no true cytoskeleton.

Difficulty Level

Intermediate – routinely tested in first-year biology with emphasis on comparison and exceptions.

Common Traps (3–5 factual traps)

Trap: All cells with cell walls have peptidoglycan – Fact: Only bacteria have peptidoglycan; plant cell walls are made of cellulose, fungal walls of chitin.
Trap: Ribosome size is the same across all cells – Fact: Prokaryotes have 70S ribosomes; eukaryotes have 80S in cytoplasm (but 70S in mitochondria and chloroplasts).
Trap: Mitochondria are found in all eukaryotic cells – Fact: Mature red blood cells in mammals lack mitochondria.
Trap: Prokaryotes have no internal membranes – Fact: Some prokaryotes (e.g., cyanobacteria) have internal membrane systems for photosynthesis.
Trap: The nucleus evolved from invagination of the plasma membrane – Fact: The nuclear envelope likely originated from infoldings of the plasma membrane in early eukaryotes (endomembrane hypothesis), but this is distinct from mitochondria/chloroplast origin.

Practice MCQs (5–7 questions)

Question: Which of the following is a feature shared by both prokaryotic and eukaryotic cells?
A) Membrane-bound nucleus
B) Mitochondria
C) Phospholipid bilayer plasma membrane
D) 80S ribosomes
Answer: C
Explanation: Both cell types have a phospholipid bilayer as the plasma membrane.
Why the top distractor is wrong: D (80S ribosomes) is only found in eukaryotic cytoplasm; prokaryotes have 70S.

Question: Which structure is found in plant cells but not in animal cells?
A) Lysosome
B) Central vacuole
C) Golgi apparatus
D) Ribosome
Answer: B
Explanation: The large central vacuole is a defining feature of plant cells.
Why the top distractor is wrong: A (lysosome) is present in animal cells but rare in plants, which use vacuoles for degradation.

Question: Which of the following provides evidence for the endosymbiotic theory?
A) Eukaryotes have linear DNA
B) Mitochondria have 70S ribosomes and circular DNA
C) Prokaryotes lack a nucleus
D) Eukaryotes have a cytoskeleton
Answer: B
Explanation: Mitochondria resemble bacteria in ribosome type and genome structure.
Why the top distractor is wrong: A is a general eukaryotic trait but not evidence of endosymbiosis.

Question: A bacterial cell is identified that lacks a cell wall. Which of the following best describes this organism?
A) Archaea
B) Mycoplasma
C) Cyanobacteria
D) Eukaryote
Answer: B
Explanation: Mycoplasma is a genus of bacteria that naturally lack a cell wall.
Why the top distractor is wrong: A (Archaea) may lack peptidoglycan but typically have cell walls made of other materials.

Question: Where is DNA located in a eukaryotic liver cell?
A) Nucleoid only
B) Nucleus and mitochondria
C) Nucleus only
D) Cytoplasm and nucleus
Answer: B
Explanation: Eukaryotic nuclear DNA is in the nucleus; mitochondrial DNA is in the mitochondria.
Why the top distractor is wrong: C ignores the presence of mitochondrial DNA, which is essential for organelle function.

Question: Which of the following is true of ribosomes in chloroplasts?
A) They are 80S, like cytoplasmic ribosomes
B) They are 70S, like prokaryotic ribosomes
C) They are synthesized in the Golgi
D) They are absent in plant cells
Answer: B
Explanation: Chloroplasts contain 70S ribosomes, supporting their prokaryotic origin.
Why the top distractor is wrong: A is incorrect because 80S ribosomes are only in the eukaryotic cytoplasm.

Question: Which of the following structures is present in eukaryotes but absent in prokaryotes?
A) Plasma membrane
B) Ribosomes
C) Endoplasmic reticulum
D) DNA
Answer: C
Explanation: The endoplasmic reticulum is a membrane-bound organelle unique to eukaryotes.
Why the top distractor is wrong: A, B, and D are present in both cell types.

Last?Minute Revision (20–25 one?liners)

• Prokaryotic cell size: 0.1–5.0 ?m; eukaryotic: 10–100 ?m.
• Prokaryotes store DNA in the nucleoid; eukaryotes in the nucleus.
• Prokaryotic ribosome = 70S; eukaryotic cytoplasmic ribosome = 80S.
• Mitochondria and chloroplasts have 70S ribosomes and circular DNA – evidence of endosymbiosis.
• Bacteria cell wall contains peptidoglycan; archaea do not.
• Plant cell wall = cellulose; fungal = chitin; animal cells = no cell wall.
• Both cell types have a phospholipid bilayer plasma membrane.
• Eukaryotes have membrane-bound organelles; prokaryotes do not.
• Mycoplasma – no cell wall, smallest known cells.
• Mature human red blood cells lack a nucleus and mitochondria.
• Nuclear envelope has double membrane and nuclear pores.
• Nucleolus = site of rRNA synthesis and ribosome subunit assembly.
• Smooth ER = lipid synthesis; rough ER = protein synthesis (due to ribosomes).
• Golgi apparatus = modifies, sorts, packages proteins for secretion.
• Lysosomes contain acid hydrolases; active at low pH.
• Plant vacuole maintains turgor pressure and stores ions and metabolites.
• Mitochondria = double membrane, cristae, site of ATP synthesis.
• Chloroplasts = thylakoids, grana, site of photosynthesis.
• Eukaryotic flagella = 9+2 microtubule arrangement; prokaryotic = flagellin-based, rotating.
• Cilia = short, numerous; only in eukaryotes.
• Plasmids = small circular DNA; common in bacteria, rare in eukaryotes.
• Cytoskeleton components: actin (microfilaments), intermediate filaments, tubulin (microtubules).
• Prokaryotes have FtsZ (tubulin homolog) for division; no true cytoskeleton.
• Cyanobacteria perform photosynthesis using internal thylakoid membranes, not chloroplasts.
• Endosymbiotic theory: mitochondria from aerobic bacteria, chloroplasts from cyanobacteria.