BIO101 - Introductory Biology Flashcards

Question 1

What are the three main tenets of Cell Theory?

Accepted Answer

1. All living organisms are composed of one or more cells.
2. The cell is the basic unit of structure and organization in organisms.
3. All cells arise from pre-existing cells.

Question 2

Define a Prokaryotic Cell.

Accepted Answer

A simple, single-celled organism that lacks a membrane-bound nucleus and other membrane-bound organelles. Its genetic material (DNA) is located in the cytoplasm in a region called the nucleoid. Examples include bacteria and archaea.

Question 3

Define a Eukaryotic Cell.

Accepted Answer

A cell that possesses a membrane-bound nucleus and other membrane-bound organelles, such as mitochondria, endoplasmic reticulum, and Golgi apparatus. These cells are typically larger and more complex than prokaryotic cells and can be single-celled or part of multicellular organisms (e.g., plants, animals, fungi, protists).

Question 4

List key differences between Prokaryotic and Eukaryotic cells.

Accepted Answer

1.  **Nucleus:** Prokaryotic (No), Eukaryotic (Yes)
2.  **Organelles:** Prokaryotic (No membrane-bound), Eukaryotic (Many membrane-bound)
3.  **Size:** Prokaryotic (Smaller, 0.1-5 $\mu m$), Eukaryotic (Larger, 10-100 $\mu m$)
4.  **DNA:** Prokaryotic (Circular, in nucleoid), Eukaryotic (Linear, in nucleus)
5.  **Ribosomes:** Prokaryotic (Smaller 70S), Eukaryotic (Larger 80S)
6.  **Cell Wall:** Prokaryotic (Present, peptidoglycan), Eukaryotic (Present in plants/fungi, absent in animals)

Question 5

What is the primary function of the Nucleus in a eukaryotic cell?

Accepted Answer

The nucleus houses the cell's genetic material (DNA) organized into chromosomes. It controls cell growth, metabolism, and reproduction by regulating gene expression and protein synthesis.

Question 6

What is the function of Mitochondria?

Accepted Answer

Often called the "powerhouses" of the cell, mitochondria are responsible for cellular respiration, generating most of the cell's supply of adenosine triphosphate (ATP) by converting glucose and oxygen into energy.

Question 7

Describe the functions of the Rough ER and Smooth ER.

Accepted Answer

1.  **Rough ER:** Studded with ribosomes, it synthesizes and modifies proteins destined for secretion or insertion into membranes.
2.  **Smooth ER:** Lacks ribosomes, involved in lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions.

Question 8

What is the role of the Golgi Apparatus (or Golgi complex)?

Accepted Answer

The Golgi apparatus modifies, sorts, and packages proteins and lipids synthesized in the ER into vesicles for secretion or delivery to other organelles. It acts as the cell's "post office."

Question 9

What is the function of Ribosomes?

Accepted Answer

Ribosomes are responsible for protein synthesis (translation). They read messenger RNA (mRNA) sequences and assemble amino acids into polypeptide chains. They can be free in the cytoplasm or attached to the Rough ER.

Question 10

What is the function of Lysosomes?

Accepted Answer

Lysosomes are membrane-bound organelles containing digestive enzymes. They break down waste materials, cellular debris, and foreign invaders (like bacteria), and recycle cellular components through autophagy.

Question 11

Describe the function of Vacuoles, noting differences in plant and animal cells.

Accepted Answer

1.  **Plant Cells:** Often have a large central vacuole that stores water, nutrients, and waste products, maintains turgor pressure, and helps with cell growth.
2.  **Animal Cells:** Have smaller, temporary vacuoles involved in storage, transport, and waste removal.

Question 12

What is the function of Chloroplasts?

Accepted Answer

Found in plant cells and some protists, chloroplasts are the sites of photosynthesis. They convert light energy into chemical energy (glucose) using chlorophyll.

Question 13

What is the function of the Cell Wall?

Accepted Answer

A rigid outer layer found in plant cells (cellulose), fungi (chitin), and bacteria (peptidoglycan). It provides structural support, protection, and prevents excessive water uptake. Animal cells lack a cell wall.

Question 14

Describe the function of the Plasma Membrane.

Accepted Answer

A selectively permeable phospholipid bilayer that surrounds the cell, regulating the passage of substances into and out of the cell. It also plays roles in cell signaling and adhesion.

Question 15

Describe the structure of DNA.

Accepted Answer

DNA (Deoxyribonucleic Acid) is a double helix composed of two polynucleotide strands. Each strand consists of a sugar-phosphate backbone and nitrogenous bases (Adenine (A), Guanine (G), Cytosine (C), Thymine (T)). A always pairs with T, and G always pairs with C, via hydrogen bonds.

Question 16

Explain the process of DNA Replication.

Accepted Answer

DNA replication is the semi-conservative process by which a cell makes an exact copy of its DNA. The double helix unwinds, and each original strand serves as a template for the synthesis of a new complementary strand, resulting in two identical DNA molecules, each with one old and one new strand. Key enzymes include DNA helicase, DNA polymerase, and DNA ligase.

Question 17

What is the Central Dogma of Molecular Biology?

Accepted Answer

The Central Dogma describes the flow of genetic information within a biological system: DNA is transcribed into RNA, and RNA is translated into protein. It can be summarized as: DNA $\rightarrow$ RNA $\rightarrow$ Protein.

Question 18

Define Transcription.

Accepted Answer

Transcription is the process where the genetic information encoded in DNA is copied into a messenger RNA (mRNA) molecule. RNA polymerase unwinds a segment of DNA and synthesizes a complementary mRNA strand using one of the DNA strands as a template.

Question 19

Define Translation.

Accepted Answer

Translation is the process where the genetic information carried by mRNA is decoded to synthesize a specific protein. Ribosomes read the mRNA codons, and transfer RNA (tRNA) molecules bring the corresponding amino acids to the ribosome, where they are linked to form a polypeptide chain.

Question 20

Differentiate between Genotype and Phenotype.

Accepted Answer

1.  **Genotype:** The genetic makeup of an organism, referring to the specific alleles an individual possesses for a particular gene (e.g., `BB`, `Bb`, `bb`).
2.  **Phenotype:** The observable physical or biochemical characteristics of an organism, resulting from the interaction of its genotype with the environment (e.g., blue eyes, tall height).

Question 21

What is a Punnett Square and how is it used?

Accepted Answer

A Punnett Square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross. It illustrates all possible combinations of alleles from the parents and the probability of each outcome.

Question 22

State Mendel's Law of Segregation.

Accepted Answer

Mendel's Law of Segregation states that during the formation of gametes (sperm and egg cells), the two alleles for a heritable character separate (segregate) from each other, so that each gamete carries only one allele for that character.

Question 23

State Mendel's Law of Independent Assortment.

Accepted Answer

Mendel's Law of Independent Assortment states that the alleles for different genes assort independently of one another during gamete formation. This means that the inheritance of one gene does not influence the inheritance of another gene, provided they are on different chromosomes or far apart on the same chromosome.

Question 24

Explain the four principles of Natural Selection.

Accepted Answer

1.  **Variation:** Individuals within a population exhibit variation in their traits.
2.  **Heritability:** Some of this variation is heritable (passed from parents to offspring).
3.  **Overproduction/Competition:** Organisms produce more offspring than can survive, leading to competition for resources.
4.  **Differential Survival & Reproduction:** Individuals with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits to their offspring.

Question 25

Define Speciation.

Accepted Answer

Speciation is the evolutionary process by which new and distinct species arise from an ancestral population. This typically occurs when populations become reproductively isolated, leading to genetic divergence over time due to natural selection, genetic drift, and mutation.

BIO101 - Introductory Biology

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