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MCAT Biology Review, Chapter1 unit 1.1-1.5 2025 Latest Questions and Answers
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MCAT Biology Review, Chapter1 unit 1.1-1.5 2025 Latest Questions and Answers
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MCAT Biology Review, Chapter1 unit 1.1-1.5 2025 Latest Questions and Answers
1. Who is credited with first observing and describing cells in 1665 using a microscope? - correct answer-
Robert Hooke is credited with first observing and describing cells in 1665 using a crude compound
microscope on a piece of cork.
2. What three original tenets formed the basis of the cell theory? - correct answer-The three original
tenets of cell theory were: All living things are composed of cells, the cell is the basic functional unit of
life, and cells arise only from pre-existing cells.
3. Which scientist in the 19th century demonstrated that diseased cells arise from normal cells? - correct
answer-Rudolph Virchow demonstrated in 1850 that diseased cells could arise from normal cells in
normal tissues.
4. What is the fourth tenet that was later added to the cell theory principles? - correct answer-The fourth
tenet added later states that cells carry genetic information in the form of deoxyribonucleic acid (DNA)
which is passed on from parent to daughter cells.
5. Why do viruses pose a dilemma or challenge to strictly adhering to the tenets of cell theory? - correct
answer-Viruses pose a dilemma because they are unable to reproduce on their own, violating the tenets
that cells arise from pre-existing cells and carry DNA as genetic material (since some viruses use RNA).
6. What technological advancement allowed early scientists to visualize cells for the first time? - correct
answer-The technological advance of microscopes, even crude early ones, allowed scientists to first
visualize smaller cell structures.
7. How did the understanding of cells as the basic units of life develop over time? - correct answer-The
understanding developed gradually, from initially seeing organisms as inseparable wholes, to observing
cells as distinct structures, to recognizing tissues are made of cells, to realizing cells'functions determine
tissue/organism functions.
8. What is the significance of Rudolph Virchow's contribution to cell theory? - correct answer-Rudolph
Virchow's significant contribution was demonstrating that diseased cells originate from normal cells, not
spontaneously.
9. What are the two different types of nucleic acids that can carry genetic information in cells and
viruses? - correct answer-The two types of nucleic acids mentioned are deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA).
10. How does the passage highlight the evolving nature of scientific theories based on new discoveries
and evidence? - correct answer-The passage highlights how cell theory evolved as a scientific theory
based on new evidence from improved instrumentation and experimental observations over centuries.
11. According to the passage, why were organisms initially perceived as inseparable wholes prior to the
1600s? - correct answer-Organisms were perceived as inseparable wholes prior to the 1600s because the
inability to see smaller structures through simple optical instruments like magnifying glasses.
,12. Who was the first person to view a living cell under a microscope and in what year did this occur? -
correct answer-Anton van Leeuwenhoek was the first to view a living cell under a microscope in 1674.
13. What analogy did Robert Hooke use when he first described the cellular structures he observed in
cork? - correct answer-When Robert Hooke first described the cellular structures he observed in cork, he
compared the spaces within the cork to the small rooms of a monastery, known as cells.
14. How did the understanding that tissues are made up of cells contribute to the development of cell
theory? - correct answer-The understanding that tissues are made up of cells contributed to cell theory
by showing that the function of a tissue depends on the functions of its component cells.
15. What is the significance of cells being described as the "basic functional units of life"? - correct
answer-Describing cells as the "basic functional units of life" is significant because it establishes cells as
the fundamental building blocks that enable life processes in organisms.
16. How did advances in molecular biology lead to the addition of the fourth tenet to cell theory? -
correct answer-Advances in molecular biology, allowing scientists to study DNA and genetic processes,
led to the addition of the fourth tenet about cells carrying genetic material.
17. Why is the role of genetic material like DNA and RNA an important consideration in cell theory? -
correct answer-The role of genetic material like DNA and RNA is important in cell theory because it
explains how cells can replicate and pass on information from one generation to the next.
18. How do viruses challenge the traditional definition of a cell according to cell theory principles? -
correct answer-Viruses challenge the traditional cell theory definition because they are not cells
themselves, require host cells to replicate, and may use RNA rather than DNA as genetic material.
19. What does the passage suggest about the dynamic nature of scientific theories and their ability to
evolve over time? - correct answer-The passage suggests scientific theories are dynamic and can evolve
as new evidence emerges from improved research methods and technological advances over time.
20. According to the passage, what criteria must be met for something to be considered a cell based on
modern cell theory? - correct answer-According to modern cell theory, to be considered a cell something
must be a distinct, self-contained unit capable of metabolic processes and replication while carrying
genetic instructions in the form of nucleic acids.
21. What property of cork cells allowed Robert Hooke to observe their structures, even though they
were non-living cells? - correct answer-Cork cells were desiccated (dried out) nonliving cells, which
allowed Robert Hooke to observe their cellular structures since the cell contents had been removed.
22. How did the observations of Robert Hooke and Anton van Leeuwenhoek differ in terms of the cells
they viewed? - correct answer-Robert Hooke observed non-living cork cells, while Anton van
Leeuwenhoek was the first to view living cells under a microscope.
23. According to the passage, what was Rudolph Virchow's key insight regarding the origin of diseased
cells? - correct answer-Rudolph Virchow's key insight was that diseased cells arise from normal cells
within normal tissues, rather than appearing spontaneously.
,24. Why is the fourth tenet about genetic material considered an addition to the original form of cell
theory? - correct answer-The fourth tenet about cells carrying genetic material like DNA was considered
an addition because it was not part of the original three tenets forming the initial cell theory.
25. Explain the potential conflict between viruses and the third tenet of cell theory. - correct answer-
Viruses potentially conflict with the third tenet because they are unable to reproduce on their own,
instead requiring a host cell to replicate.
26. How does the passage distinguish between cells and organisms in terms of their respective
functions? - correct answer-The passage distinguishes cells as the basic functional units carrying out
processes that enable the larger functions of the entire organism.
28. What does the passage imply about the importance of understanding cell biology for comprehending
larger biological systems? - correct answer-The passage implies understanding cell biology is crucial for
comprehending how the human body as a whole organism reacts and functions.
28. Describe the role that improvements in microscopy played in the development of cell theory. -
correct answer-Improvements in microscopy, from crude early microscopes to more advanced ones,
allowed the visualization of smaller cellular structures over time.
29. According to the passage, what criteria must a structure meet to be considered a living cell based on
modern cell theory? - correct answer-According to modern cell theory, to be considered a living cell, a
structure must be a distinct unit capable of metabolic processes, self-replication, and carrying genetic
instructions like DNA or RNA.
30. What is the key structural difference between prokaryotic and eukaryotic cells in terms of their
genetic material? - correct answer-The key structural difference is that eukaryotic cells contain a true
nucleus enclosed in a membrane, while prokaryotic cells do not have a nucleus. The genetic material in
eukaryotes is contained within the nucleus.
31. Describe the structure and function of the mitochondria in eukaryotic cells? - correct answer-
Mitochondria have a double membrane - an outer membrane and an inner membrane folded into
cristae. The space between these two membranes is called the intermembrane space, while the inner
region is the matrix. Mitochondria are involved in energy production via oxidative phosphorylation and
the electron transport chain located in the cristae.
32. How do lysosomes and endosomes work together in eukaryotic cells? - correct answer-Lysosomes
contain hydrolytic enzymes that can break down various substrates. Endosomes transport, package, and
sort materials, delivering some to lysosomes for degradation by the hydrolytic enzymes.
33. Distinguish between the roles of the rough endoplasmic reticulum (RER) and smooth endoplasmic
reticulum (SER). - correct answer-The rough ER is studded with ribosomes and is involved in the synthesis
of proteins destined for secretion or membranes. The smooth ER lacks ribosomes and functions in lipid
synthesis, carbohydrate metabolism, and detoxification.
34. What is the primary function of the Golgi apparatus in modifying and sorting proteins? - correct
answer-The primary role of the Golgi apparatus is to receive proteins from the ER, modify them by
adding groups like carbohydrates, package them into vesicles, and sort them for delivery to their
intended cellular locations or secretion.
, 35. According to the endosymbiotic theory, what is the proposed origin of mitochondria and
chloroplasts? - correct answer-According to the endosymbiotic theory, mitochondria and chloroplasts
originated when a prokaryotic cell engulfed another prokaryote, leading to a symbiotic relationship
where the engulfed cell became an organelle.
36. How do peroxisomes contribute to lipid metabolism in eukaryotic cells? - correct answer-
Peroxisomes contain enzymes involved in breaking down very long chain fatty acids through beta-
oxidation. They also contribute to phospholipid biosynthesis and the pentose phosphate pathway.
37. What are the three main components of the cytoskeleton and their respective functions? - correct
answer-The three main cytoskeletal components are: microfilaments (actin), microtubules (tubulin), and
intermediate filaments. They provide structural support, enable cell motility, and act as transport routes
within the cell.
38. Describe the structural differences between microfilaments, microtubules, and intermediate
filaments. - correct answer-Microfilaments are solid actin polymers, microtubules are hollow tubulin
polymers, and intermediate filaments are a diverse group of fibrous proteins like keratin and lamins.
They differ in structure and composition.
39. How are epithelial tissues classified based on the number of cell layers and cell shapes? - correct
answer-Epithelial tissues are classified as simple (single layer), stratified (multiple layers), or
pseudostratified based on number of layers. Cell shapes like squamous, cuboidal or columnar are also
used for classification.
40. What is the main role of connective tissues in relation to epithelial tissues? - correct answer-The
main role of connective tissues is to provide structural support, bind tissues together, and secrete an
extracellular matrix that forms the stroma or framework on which epithelial tissues can function.
41. Provide examples of different types of connective tissues mentioned in the passage. - correct answer-
Examples of connective tissues are bone, cartilage, tendons, ligaments, adipose tissue, and blood.
42. How do epithelial cells exhibit polarity in their structure and functions? - correct answer-Epithelial
cells are often polarized, with an apical surface facing a body cavity/lumen and a basal surface
interacting with underlying connective tissue. This polarity allows different functions on each surface.
43. Why is the localization of DNA in the nucleus important for eukaryotic cells? - correct answer-
Localizing DNA in the nucleus allows separation of transcription (in the nucleus) from translation (in the
cytoplasm), and compartmentalization of genetic processes in eukaryotes.
44. What is the significance of the 9+2 microtubule arrangement in cilia and flagella? - correct answer-
The 9+2 arrangement of microtubules, with 9 doublets surrounding 2 central tubules, is the unique
structural feature providing motility to cilia and flagella in eukaryotic cells.
45. What is the role of the nucleolus within the nucleus? - correct answer-The nucleolus is a sub-
compartment within the nucleus where ribosomal RNA (rRNA) is synthesized. It takes up about 25% of
the nuclear volume.
46. Explain the process of oxidative phosphorylation that occurs in the mitochondria. - correct answer-In
oxidative phosphorylation, the electron transport chain in the mitochondrial cristae pumps protons from
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