BIO101 — Introduction to Biology: Midterm & Finalterm Solved MCQs and Subjective

Introduction to Biology covers what life is, cells, the chemistry of life, membranes and enzymes, respiration, DNA and protein synthesis, genetics, evolution, classification, ecology and PCR. This solved post gives you 30 verified items for Virtual University of Pakistan: 10 Midterm MCQs from Lectures 1-22, 10 Finalterm MCQs from Lectures 23-45, and 5 Midterm plus 5 Finalterm subjective questions, each with its correct answer and handout lesson reference. Practice every question instantly in the quiz for this course. Take the quiz: https://virtualustaad.blogspot.com/p/solvedmcqs.html?code=BIO101

1. Midterm Solved MCQs

Q1. The smallest, most fundamental unit of life is the: A) Atom B) Molecule C) Cell D) Organ. Correct answer: C — Cell. Reference: VU handout, Lesson 2 — Cells, the basic unit of life.

Q2. The ability of an organism to maintain a stable internal environment is termed: A) Metabolism B) Homeostasis C) Adaptation D) Evolution. Correct answer: B — Homeostasis. Reference: VU handout — Characteristics of life; regulation.

Q3. Which of the following best describes a scientific theory? A) A guess with no evidence B) A belief that cannot be tested C) A well-tested explanation supported by a large body of evidence D) A single unrepeated observation. Correct answer: C — A well-tested explanation supported by a large body of evidence. Reference: VU handout, Lesson 1 — What is Life?; the scientific method.

Q4. Which of the following correctly identifies a prokaryotic organism? A) A mushroom B) A bacterium C) An amoeba D) A fern. Correct answer: B — A bacterium. Reference: VU handout, Lesson 2 — Prokaryotic and eukaryotic cells.

Q5. The main feature that distinguishes a prokaryotic cell from a eukaryotic cell is the: A) Presence of ribosomes B) Presence of a cell wall C) Absence of a membrane-bound nucleus D) Absence of DNA. Correct answer: C — Absence of a membrane-bound nucleus. Reference: VU handout, Lesson 2 — Prokaryotic vs eukaryotic cells.

Q6. The pH of a neutral solution (pure water at 25 °C) is: A) 0 B) 5 C) 7 D) 14. Correct answer: C — 7. Reference: VU handout — Chemistry of life; acids, bases and pH.

Q7. Water can absorb a large amount of heat with only a small rise in temperature because of its: A) Low density B) High specific heat, due to hydrogen bonding C) Non-polar molecules D) Low boiling point. Correct answer: B — High specific heat, due to hydrogen bonding. Reference: VU handout — Chemistry of life; properties of water.

Q8. Cells make polymers from monomers by which chemical reaction? A) Hydrolysis B) Dehydration (condensation) reaction C) Oxidation D) Photolysis. Correct answer: B — Dehydration (condensation) reaction. Reference: VU handout — Molecules of life; polymers.

Q9. The main components of cell membranes are: A) Triglycerides B) Phospholipids C) Steroids only D) Cellulose. Correct answer: B — Phospholipids. Reference: VU handout — Cell structure; the plasma membrane.

Q10. The organelle known as the "powerhouse of the cell", where most ATP is produced by aerobic respiration, is the: A) Ribosome B) Golgi apparatus C) Lysosome D) Mitochondrion. Correct answer: D — Mitochondrion. Reference: VU handout — Cell structure; organelles.

2. Finalterm Solved MCQs

Q1. Photosynthesis converts: A) Chemical energy to mechanical energy B) Sunlight to mechanical energy C) Sunlight to chemical energy D) Mechanical energy to chemical energy. Correct answer: C — Sunlight to chemical energy. Reference: VU handout — Photosynthesis.

Q2. In a DNA double helix, adenine pairs with: A) Guanine B) Cytosine C) Thymine D) Uracil. Correct answer: C — Thymine. Reference: VU handout — DNA structure; the genetic code.

Q3. The process by which the information in a gene directs the synthesis of a protein is called: A) Gene expression B) Replication C) Mutation D) Cloning. Correct answer: A — Gene expression. Reference: VU handout — DNA and protein synthesis.

Q4. Meiosis produces: A) Two genetically identical diploid cells B) Four genetically different haploid cells C) Two genetically different haploid cells D) Four genetically identical diploid cells. Correct answer: B — Four genetically different haploid cells. Reference: VU handout — Cell reproduction; meiosis.

Q5. Mendel's law of segregation states that: A) Genes on different chromosomes are inherited independently B) The two alleles of a gene separate during gamete formation C) Dominant alleles always mask recessive alleles in every generation D) Offspring always resemble one parent exactly. Correct answer: B — The two alleles of a gene separate during gamete formation. Reference: VU handout — Genetics; Mendel's laws.

Q6. Selective breeding of livestock for desired traits is an example of: A) Natural selection B) Artificial selection C) Genetic drift D) Mutation. Correct answer: B — Artificial selection. Reference: VU handout — Evolution; selection.

Q7. The branch of biology concerned with the naming and classifying of organisms is: A) Informatics B) Taxonomy C) Genomics D) Ecology. Correct answer: B — Taxonomy. Reference: VU handout — Diversity and classification of organisms.

Q8. The number of individuals in a population per unit area is termed the: A) Population growth rate B) Population density C) Carrying capacity D) Biotic potential. Correct answer: B — Population density. Reference: VU handout — Ecology; populations.

Q9. Mycorrhizal fungi break down minerals for plants, and the plants produce sugars for the fungi. This interaction is an example of: A) Parasitism B) Competition C) Commensalism D) Mutualism. Correct answer: D — Mutualism. Reference: VU handout — Ecology; species interactions.

Q10. PCR (polymerase chain reaction) uses which heat-stable enzyme? A) DNA ligase B) Taq polymerase C) Reverse transcriptase D) Helicase. Correct answer: B — Taq polymerase. Reference: VU handout, Lesson 45 — The steps of PCR.

3. Midterm Subjective

Q1. What is life? List and explain the characteristics of living organisms. Answer: Biology is the study of life, and living things share a set of characteristics: (1) Order — living things are highly organised, from atoms to cells to organisms; (2) Reproduction — organisms produce offspring like themselves, passing on DNA; (3) Growth and development — organisms grow and change in a regulated way; (4) Energy processing — organisms take in energy and use it (metabolism is the sum of all chemical reactions in the body); (5) Response to the environment — organisms sense and react to stimuli (e.g. receptors on the cell surface made of proteins); (6) Regulation — maintaining a stable internal environment (homeostasis); and (7) Evolutionary adaptation — populations change over generations by natural selection. A virus, for example, fails several of these tests (it cannot reproduce or carry out metabolism on its own), which is why it is not classed as fully alive. Reference: VU handout, Lesson 1 — What is Life?

Q2. Distinguish prokaryotic and eukaryotic cells, with examples. Answer: Prokaryotic cells (bacteria and archaea) are smaller and simpler: they have no membrane-bound nucleus — their DNA lies in a nucleoid region — and no membrane-enclosed organelles; most have a cell wall and divide by binary fission. Eukaryotic cells (animals, plants, fungi, protists) are larger and have a true nucleus enclosing the DNA, plus membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus and (in plants) chloroplasts. Both kinds of cell have a plasma membrane, cytoplasm, ribosomes and DNA as genetic material. Example: Escherichia coli is prokaryotic; a human liver cell is eukaryotic. Reference: VU handout, Lesson 2 — Cells; prokaryotic vs eukaryotic.

Q3. Describe the fluid mosaic model of the cell membrane. Answer: The fluid mosaic model describes the plasma membrane as a phospholipid bilayer in which proteins are embedded like a mosaic, and the whole structure is fluid rather than rigid. Each phospholipid has a hydrophilic (water-loving) head facing outward and two hydrophobic (water-fearing) fatty-acid tails facing inward, so the bilayer forms spontaneously in water. Proteins float in the bilayer: integral proteins span it (channels, carriers, receptors — the surface receptors that let a cell sense and respond to stimuli are proteins), while peripheral proteins sit on the surface. Cholesterol (in animal cells) and carbohydrates (as glycolipids/glycoproteins) are also present. The membrane is selectively permeable: small non-polar molecules cross freely, while ions and large polar molecules need transport proteins. Reference: VU handout — Cell structure; the plasma membrane.

Q4. How do enzymes work? Explain activation energy, the active site, and the lock-and-key vs induced-fit models. Answer: An enzyme is a biological catalyst, usually a protein, that speeds up a chemical reaction without being consumed. It works by lowering the activation energy — the energy barrier that must be overcome for a reaction to proceed — so more substrate molecules can react. The reaction happens at the enzyme's active site, a pocket shaped to bind the substrate. In the lock-and-key model the active site is a rigid shape exactly complementary to the substrate. In the induced-fit model (now preferred) the active site is flexible: it changes shape slightly to fit the substrate snugly once it binds, straining the substrate's bonds and making the reaction easier. Enzymes are specific — each acts on particular substrates — and their activity is affected by temperature, pH and inhibitors. Reference: VU handout — Energy and enzymes.

Q5. Describe aerobic cellular respiration: its stages and the net ATP yield. Answer: Aerobic respiration oxidises glucose completely to CO2 and water, releasing energy stored as ATP. It has three main stages: (1) Glycolysis in the cytoplasm — glucose (6C) is split into two pyruvate molecules, with a net gain of 2 ATP and 2 NADH; (2) The Krebs (citric acid) cycle in the mitochondrial matrix — each pyruvate is converted to acetyl-CoA and oxidised, releasing CO2 and producing NADH, FADH2 and 1 ATP (GTP) per turn; (3) The electron transport chain on the inner mitochondrial membrane — NADH and FADH2 donate electrons; the energy released pumps protons across the membrane, and ATP synthase uses the proton gradient to make most of the ATP, with oxygen as the final electron acceptor (forming water). Overall, one glucose yields about 30-32 ATP (older textbooks say 36-38). Without oxygen, cells use fermentation instead, which yields only the 2 net ATP of glycolysis. Reference: VU handout — Cell respiration.

4. Finalterm Subjective

Q1. Describe the structure of DNA and the process of DNA replication. Answer: DNA is a double helix of two antiparallel strands. Each strand is a polymer of nucleotides (deoxyribose sugar + phosphate + one of four bases: adenine, thymine, guanine, cytosine). The bases pair by hydrogen bonds — A with T, G with C — holding the two strands together, and the sequence of bases carries genetic information. Replication is semi-conservative: each daughter double helix keeps one parental strand and one newly made strand. The steps: (1) helicase unwinds and separates the strands at the origin of replication; (2) primase lays down short RNA primers; (3) DNA polymerase adds nucleotides to the 3' end, synthesising the leading strand continuously and the lagging strand in short Okazaki fragments; (4) DNA ligase joins the fragments; (5) proofreading by the polymerase corrects most errors. The result is two identical DNA molecules, one for each daughter cell. Reference: VU handout — DNA structure and the genetic code.

Q2. Explain Mendel's laws of segregation and independent assortment with an example. Answer: Mendel studied pea plants and proposed two laws. The law of segregation: an organism carries two alleles for each gene, and they separate during gamete formation, so each gamete carries only one allele. Example: a pea plant heterozygous for seed shape (Rr) produces R and r gametes in equal numbers; self-crossing gives RR, Rr and rr offspring in a 1:2:1 ratio. The law of independent assortment: alleles of different genes sort into gametes independently of each other (when the genes are on different chromosomes). Example: a dihybrid RrYy plant produces RY, Ry, rY and ry gametes in equal numbers, giving the classic 9:3:3:1 phenotypic ratio in the offspring. These laws explain why traits are inherited in predictable ratios and why offspring vary. Reference: VU handout — Genetics; Mendel's laws.

Q3. What is natural selection? Explain Darwin's theory with an example. Answer: Natural selection is the process by which individuals with heritable traits better suited to their environment survive and reproduce more successfully, so those traits become more common in the population over generations. Darwin's theory rests on four observations: (1) organisms produce more offspring than can survive; (2) individuals vary in heritable traits; (3) this variation affects survival and reproduction (struggle for existence); and (4) the advantageous traits are passed on. Example: in the peppered moth, dark-coloured moths were rare before industrialisation but became common in soot-darkened areas because birds could not see them as easily on dark trees — the dark trait was selected for. Over long periods, natural selection acting on accumulated variation produces new species (evolution). Artificial selection is the human-directed version of the same process (e.g. selective breeding of livestock). Reference: VU handout — Evolution; natural selection.

Q4. Describe the Linnaean system of classification and binomial nomenclature. Answer: Taxonomy is the branch of biology that names and classifies organisms. Linnaeus organised life into a hierarchy of ranks: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species — each rank more specific than the one above. For example, humans are: Eukarya (domain), Animalia (kingdom), Chordata (phylum), Mammalia (class), Primates (order), Hominidae (family), Homo (genus), Homo sapiens (species). Binomial nomenclature gives every species a unique two-part Latin name: the genus name (capitalised) followed by the species epithet (lower case), both italicised — e.g. Homo sapiens, Escherichia coli. This system avoids the confusion of common names, which differ between languages and regions. Reference: VU handout — Diversity and classification of organisms.

Q5. What is PCR? Describe its three steps and its uses. Answer: PCR (polymerase chain reaction) is a laboratory technique that copies a specific DNA segment many times, producing millions of copies from a tiny starting sample. Its key ingredients are Taq polymerase (a heat-stable DNA polymerase), two primers that flank the target region, template DNA, and the four nucleotides (dNTPs). The reaction cycles through three steps: (1) Denaturation (about 94-95 °C) — heat separates the double-stranded DNA; (2) Annealing (about 50-65 °C) — the temperature is lowered so the primers bind to their complementary sequences on the template; (3) Extension (about 72 °C) — Taq polymerase extends the primers, synthesising new DNA strands. Repeating the cycle 25-35 times amplifies the target exponentially. Uses: DNA fingerprinting, diagnosis of infections and genetic diseases, cloning, forensic analysis, and preparing DNA for sequencing. Reference: VU handout, Lesson 45 — The steps of PCR.

FAQ

Q: Is the Midterm from Lectures 1-22? A: Yes — Midterm covers Lectures 1-22 and Finalterm covers Lectures 23-45.

Q: Does the quiz work from this post? A: Yes — use the 'Take the quiz' link above; the quiz is already live with Midterm 10 and Finalterm 10.

Q: Are the answers verified? A: Yes — all 30 items are marked Verified, solved independently and cross-checked against at least two independent sources.

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