Topic 1-6 Paper 1

Question 1

What are the three principles of cell theory?

Answer 1

1. All living organisms are composed of one or more cells
2. The cell is the smallest unit of life
3. All cells arise from pre-existing cells

Question 2

What evidence supports cell theory?

Answer 2

Microscopic observations: all living things contain cells
Pasteur’s experiment: Showed that new cells do no spontaneously arise
Cell division: cells come from pre-existing cells

Question 3

What are the exception to the cell theory?

Answer 3

Striated muscle cells: Multi-nucleated and very large
Aseptate fungal hyphae: Continuous cytoplasm with multiple nuclei
Giant Algae (Acetabularia): Can be up to 10cm long but contain only one nucleus

Question 4

What are the seven functions of life?

Answer 4

MR H GREN

Metabolism: Chemical reactions inside the cell (ex. Respiration)
Reproduction: Producing offspring (asexual or sexual)
Homeostasis: Maintaining internal balance (ex. Temperature)
Growth: Increase in side or number of cells
Response: Reacting to stimuli in the environment
Excretion: Removal of metabolic waste (ex. CO2)
Nutrition: Obtaining fod for energy and materials

Question 5

How does surface area to volume ration affect cell size?

Answer 5

Smaller cells have a larger SA:V ratio, allowing efficient diffusion of nutrients and waste removal.
Larger cells have a smaller SA:V ratio, making diffusion inefficient, leading to division or adaptations (e.g., folding membranes).

Question 6

What are emergent properties?

Answer 6

Properties that arise from the interaction of individual components in a system (e.g., tissues forming an organ).

Question 7

What are the differences between prokaryotic and eukaryotic cells?

Answer 7

Nucleus: No nucleus (nucleoid) [prokaryotic] ,True nucleus with nuclear membrane [eukaryotic]
DNA Structure: Circular, naked DNA [prokaryotic], Linear DNA with histones [eukaryotic]
Organelles: No membrane-bound organelles [prokaryotic],Has organelles (e.g., mitochondria, ER) [eukaryotic]
Ribosomes: 70S ribosomes [prokaryotic],80S ribosomes [eukaryotic]
Size: Smaller (1-5 μm) [prokaryotic],Larger (10-100 μm) [eukaryotic]

Question 8

What are the functions of organelles in eukaryotic cells?

Answer 8

Nucleus: Contains genetic material, controls cell activities.
Rough ER: Synthesizes and transports proteins.
Smooth ER: Synthesizes lipids, detoxifies substances.
Golgi apparatus: Modifies, packages, and sorts proteins for secretion.
Lysosomes: Contains hydrolytic enzymes for digestion (only in animal cells).
Mitochondria: Site of ATP production via aerobic respiration.
Chloroplasts: Site of photosynthesis (plants only).
Ribosomes: Synthesizes proteins (80S in eukaryotes, 70S in prokaryotes).
Vacuole: Storage of water, nutrients, and waste.

Question 9

What is the fluid mosaic model of the membrane?

Answer 9

Describes the phospholipid bilayer with embedded proteins that allow flexibility.

Fluid: Phospholipids move laterally.
Mosaic: Proteins are scattered throughout the bilayer.

Question 10

What is the role of cholesterol in animal cell membranes?

Answer 10

Reduces membrane fluidity at high temperatures.
Prevents solidification at low temperatures.
Helps maintain membrane structure.

Question 11

What are the functions of membrane proteins?

Answer 11

Mnemonic: TRACIE

Transport: Channels and pumps for substances.
Receptors: Detect hormones and neurotransmitters.
Adhesion: Cell-to-cell attachment.
Cell recognition: Glycoproteins act as ID tags.
Intercellular joining: Tight junctions in tissues.
Enzymes: Catalyze reactions at the membrane.

Question 12

What are the types of passive transport?

Answer 12

Simple diffusion: Movement of small, non-polar molecules (e.g., O₂, CO₂) across the membrane.
Facilitated diffusion: Uses channel/carrier proteins for large or charged molecules (e.g., glucose, Na⁺).
Osmosis: Diffusion of water through a selectively permeable membrane.

Question 13

What is active transport?

Answer 13

Movement of substances against the concentration gradient using ATP (e.g., sodium-potassium pump).

Question 14

What is the difference between endocytosis and exocytosis?

Answer 14

Endocytosis: Cell engulfs material via vesicles (e.g., phagocytosis for solids, pinocytosis for liquids).
Exocytosis: Vesicles fuse with the membrane to release contents (e.g., neurotransmitter secretion).

Question 15

What did Pasteur’s experiment demonstrate?

Answer 15

Disproved spontaneous generation by showing that broth only spoiled when exposed to microbes.

Question 16

What is the endosymbiotic theory?

Answer 16

Explains how mitochondria and chloroplasts evolved from prokaryotic cells being engulfed by larger cells.

Evidence:
- Mitochondria & chloroplasts have their own DNA.
- Double membranes suggest engulfment.
- 70S ribosomes (like prokaryotes).

Question 17

What are the stages of the cell cycle?

Answer 17

Interphase (G1, S, G2): Growth and DNA replication.
Mitosis: Division of nucleus.
Cytokinesis: Division of cytoplasm.

Question 18

What happens in each miotic phase?

Answer 18

Prophase: Chromosomes condense, nuclear membrane dissolves
Metaphase: Chromosomes line up at equator
Anaphase: Sister chromatids separate and move to poles
Telophase: Nuclear membrane reforms, cytokinesis begins

Question 19

How is the cell cycle controlled?

Answer 19

Cyclins: Proteins that regulate the cycle.
Checkpoints: Ensure DNA is properly replicated before division.

Question 20

What is cancer and how does it occur?

Answer 20

Uncontrolled cell division due to mutations in oncogenes or tumor suppressor genes.
Metastasis: Cancer cells spread to other tissues.

Question 21

What are the four macromolecules essential for life?

Answer 21

Carbohydrates – Energy storage and structural support.
Lipids – Long-term energy storage, insulation, and membranes.
Proteins – Enzymes, transport, structural functions.
Nucleic Acids – Store and transmit genetic information (DNA, RNA).

Question 22

What is metabolism?

Answer 22

The sum of all enzyme-controlled reactions in an organism, including anabolism and catabolism.

Question 23

What is the difference between anabolism and catabolism?

Answer 23

Anabolism: Builds larger molecules from smaller ones using condensation reactions (e.g., protein synthesis).
Catabolism: Breaks down larger molecules into smaller ones using hydrolysis reactions (e.g., digestion).

Question 24

What are the properties of water and their biological importance?

Answer 24

Cohesion: Water molecules stick to each other. It deals with surface tension (ex., insects walking on water)
Adhesion: Water sticks to other surfaces. It deals with water transport in the xylem of plants.
High specific heat: Water resists temperature changes. Stable environment for aquatic life.
Solvent: Dissolves polar substances—transports nutrients and waste in blood.
High latent heat of vaporization: Water absorbs heat before evaporating. Cooling effect via sweating.

Question 25

Why is water a polar molecule?

Answer 25

Oxygen is electronegative, pulling electrons closer, creating a partial negative charge (O) and partial positive charges (H), leading to hydrogen bonding.

Question 26

What are the types of carbohydrates?

Answer 26

Monosaccharides: Quick energy source (Ex. Glucose, fructose, galactose) Disaccharides: Transportable energy (Ex. Maltose [glucose+glucose], lactose, sucrose) Polysaccharides: Energy storage, structural support (Ex. Starch, glycogen, cellulose)

Question 27

What is the difference between saturated and unsaturated fatty acids?

Answer 27

Saturated fats: No double bonds, solid at room temp (e.g., animal fats). Unsaturated fats: Have one or more double bonds, liquid at room temp (e.g., plant oils).

Question 28

What is the difference between cis and trans unsaturated fatty acids?

Answer 28

Cis fatty acids: Hydrogens on the same side of the double bond (natural, healthy). Trans fatty acids: Hydrogens on opposite sides (artificial, linked to heart disease).

Question 29

What is the difference between carbohydrates and lipids as energy storage molecules?

Answer 29

Carbohydrates: Short-term energy storage, easily broken down, water-soluble. Lipids: Long-term energy storage, contain more energy per gram, insoluble.

Question 30

What are the levels of protein structure?

Answer 30

Primary: Sequence of amino acids (Ex. Insulin) Secondary: Alpha-helices & beta-sheets (H-bonds) [Ex. Silk] Tertiary: 3D structure due to R-group interactions (Ex. Enzymes [lactase]) Quarternary: Multiple polypeptides forming a complex (Hemoglobin)

Question 32

What determines protein function?

Answer 32

The sequence of amino acids determines the shape, which determines the function.

Question 33

What is denaturation?

Answer 33

A loss of protein function due to high temperature or extreme pH, causing it to lose its shape.

Question 34

What is an enzyme and how does it work?

Answer 34

A biological catalyst that speeds up reactions by lowering activation energy using the lock-and-key or induced fit model.

Question 35

What factors affect enzyme activity?

Answer 35

Temperature: Increases activity until denaturation. pH: Optimal pH needed, extremes cause denaturation. Substrate concentration: Increases activity until saturation.

Question 36

What is competitive vs. non-competitive inhibition?

Answer 36

Competitive inhibition: Inhibitor binds to the active site, blocking the substrate (e.g., malonate inhibiting succinate dehydrogenase). Non-competitive inhibition: Inhibitor binds to an allosteric site, changing the enzyme's shape (e.g., cyanide inhibiting cytochrome oxidase).

Question 37

What are the structural differences between DNA and RNA?

Answer 37

Sugar: DNA (Deoxyribose); RNA (Ribose) Strands: DNA (Double-stranded); RNA (Single-stranded) Bases: DNA (A-T, G-C); RNA (A-U, G-C)

Question 38

What are the complementary base-pairing rules?

Answer 38

Adenine (A) pairs with Thymine (T) (or Uracil (U) in RNA). Guanine (G) pairs with Cytosine (C).

Question 39

What is DNA replication and why is it semi-conservative?

Answer 39

DNA replication creates two identical strands, each with one original strand and one new strand (semi-conservative model).

Question 40

What enzymes are involved in DNA replication?

Answer 40

Helicase: Unzips DNA strands. DNA polymerase: Adds nucleotides using complementary base-pairing. Ligase: Joins Okazaki fragments on the lagging strand.

Question 41

What happens in transcription?

Answer 41

DNA → mRNA in the nucleus. RNA polymerase creates mRNA using complementary base pairing.

Question 42

What happens in translation?

Answer 42

mRNA → Protein at the ribosome. mRNA: Carries genetic code. tRNA: Brings amino acids. Ribosome: Catalyzes peptide bond formation.

Question 43

What is the balanced equation for aerobic respiration?

Answer 43

Glucose + Oxygen → Carbon dioxide + Water + ATP C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Question 44

What is anaerobic respiration?

Answer 44

Occurs when oxygen is low: Animals: Glucose → Lactate + 2 ATP Yeast/Bacteria: Glucose → Ethanol + CO₂ + 2 ATP

Question 45

What are the light-dependent and light-independent reactions?

Answer 45

Light-dependent (Thylakoid): Uses light energy to make ATP and NADPH. Light-independent (Calvin Cycle, Stroma): Uses ATP and NADPH to fix CO₂ into glucose.

Question 46

What is a gene?

Answer 46

A section of DNA that codes for a specific protein or trait.

Question 47

What is a genome?

Answer 47

The entire genetic material of an organism.

Question 48

What is an allele?

Answer 48

A variant form of a gene (e.g., A or a for eye color).

Question 49

What is a gene mutation?

Answer 49

A change in the nucleotide sequence of DNA that may produce a different protein.

Question 50

What is a base substitution mutation?

Answer 50

A single nucleotide is replaced, possibly leading to an altered amino acid sequence (e.g., sickle cell anemia).

Question 51

What causes sickle cell anemia?

Answer 51

A point mutation in the HBB gene: DNA: GAG → GTG mRNA: GAG → GUG Amino acid: Glutamic acid → Valine Causes hemoglobin to form sickle-shaped red blood cells, leading to clotting and oxygen deficiency.

Question 52

What is the Human Genome Project?

Answer 52

An international project that sequenced the entire human genome, allowing better understanding of genetic diseases and evolution.

Question 53

What is the difference between prokaryotic and eukaryotic chromosomes?

Answer 53

DNA Shape: Circular (Prokaryotic), Linear (Eukaryotic) Histones: No histones (Prokaryotic), wrapped around histones (Eukaryotic) Number of Chromosomes: One single loop (Prokaryotic), multiple pairs (Eukaryotic) Plasmids: Yes (Prokaryotic), No (Eukaryotic)

Question 54

What is a karyogram?

Answer 54

A visual representation of chromosomes arranged by size and banding pattern.

Question 55

What is a karyotype?

Answer 55

The number and appearance of chromosomes in a cell.

Question 56

How can karyotypes be used to diagnose genetic disorders?

Answer 56

Trisomy 21 (Down syndrome): Three copies of chromosome 21. Klinefelter syndrome (XXY): Extra X chromosome in males. Turner syndrome (XO): Missing an X chromosome in females.

Question 57

What are homologous chromosomes?

Answer 57

Pairs of chromosomes that contain the same genes but may have different alleles (one from each parent).

Question 58

What is the diploid vs. haploid chromosome number?

Answer 58

Diploid (2n): Two sets of chromosomes (e.g., human somatic cells: 46). Haploid (n): One set of chromosomes (e.g., gametes: 23)

Question 59

What determines sex in humans?

Answer 59

The 23rd pair of chromosomes: XX → Female XY → Male (Y chromosome carries the SRY gene, which triggers male development).

Question 60

What is meiosis?

Answer 60

A form of cell division that produces four genetically unique haploid gametes.

Question 61

What are the two main purposes of meiosis?

Answer 61

- Genetic variation through crossing over and independent assortment. - Reducing chromosome number for gamete formation.

Question 62

What are the stages of meiosis?

Answer 62

- Prophase I: Chromosomes condense, homologous pairs undergo crossing over - Metaphase I: Homologous chromosomes align at equator (random assortment) - Anaphase I: Homologous chromosomes separate to opposite poles - Telophase I: Two haploid cells form - Prophase II: Chromosomes condense, no crossing over - Metaphase II: Chromosomes align at the equator - Anaphase II: Sister chromatids separate Telophase II: Four haploid cells form

Question 63

What is crossing over, and why is it important?

Answer 63

Occurs in Prophase I: Homologous chromosomes exchange segments. Increases genetic variation by shuffling alleles.

Question 64

What is independent assortment?

Answer 64

Occurs in Metaphase I: Random alignment of homologous pairs. Creates different combinations of chromosomes in gametes.

Question 65

How does nondisjunction lead to genetic disorders?

Answer 65

- Nondisjunction: Failure of chromosomes to separate in Meiosis I or II. - Leads to extra or missing chromosomes (e.g., Trisomy 21 → Down syndrome).

Question 66

What is the difference between genotype and phenotype?

Answer 66

- Genotype: The genetic makeup (e.g., BB, Bb, bb). - Phenotype: The physical expression of the genotype (e.g., brown eyes).

Question 67

What are dominant and recessive alleles?

Answer 67

- Dominant alleles (A): Expressed even if only one copy is present (AA or Aa). - Recessive alleles (a): Only expressed when homozygous (aa).

Question 68

What are codominant alleles?

Answer 68

Both alleles are expressed equally in the phenotype (e.g., AB blood type).

Question 69

What are monohybrid crosses?

Answer 69

A genetic cross examining the inheritance of one gene (e.g., eye color).

Question 70

What is a Punnett square used for?

Answer 70

Predicts the probability of offspring inheriting specific traits.

Question 71

What is sex-linked inheritance?

Answer 71

Genes located on the X chromosome affect males more often (e.g., color blindness, hemophilia).

Question 72

What is the inheritance pattern of hemophilia?

Answer 72

XᴴXᴴ × XʰY: Male offspring all normal, Female offspring all normal XᴴXʰ × XᴴY: Male offspring 50% normal, 50% carrier; Female offspring 50% normal, 50% affected XᴴXʰ × XʰY: Male offspring 50% carrier, 50% affected; Female offspring 50% normal, 50% affected

Question 73

What are the steps of PCR (Polymerase Chain Reaction)?

Answer 73

- Denaturation: Heat DNA to separate strands. - Annealing: Cool to allow primers to attach. - Extension: DNA polymerase synthesizes new DNA strands.

Question 74

What is gel electrophoresis used for?

Answer 74

Separates DNA fragments based on size using an electric field.

Question 75

What are GMOs (Genetically Modified Organisms)?

Answer 75

Organisms whose DNA has been altered using biotechnology (e.g., Bt corn produces insecticide proteins).

Question 76

What is gene transfer and how is it done?

Answer 76

Moving a gene from one organism to another using: 1. Restriction enzymes cut DNA. 2. Ligase enzyme joins DNA into a plasmid. 3. Bacteria take up the recombinant plasmid and produce the desired protein.

Question 77

What is a species?

Answer 77

A group of organisms that can interbreed and produce fertile offspring.

Question 78

What is a population?

Answer 78

A group of organisms of the same species living in the same area at the same time.

Question 79

What is a community?

Answer 79

All the populations of different species living together in an area.

Question 80

What is an ecosystem?

Answer 80

A community and its abiotic environment (e.g., water, soil, temperature).

Question 81

What are abiotic and biotic factors?

Answer 81

- Abiotic: Non-living components (e.g., light, temperature, pH, water, air). - Biotic: Living components (e.g., plants, animals, fungi, bacteria).

Question 82

What is a habitat?

Answer 82

The environment where a species lives.

Question 83

What is a niche?

Answer 83

The role of an organism in its ecosystem (e.g., food source, predators, interactions).

Question 84

What is a trophic level?

Answer 84

The position an organism occupies in a food chain. Example: Producer (T1) → Primary consumer (T2) → Secondary consumer (T3) → Tertiary consumer (T4)

Question 85

What are the different types of interactions between species?

Answer 85

- Mutualism: Both species benefit (e.g., clownfish and sea anemones). - Parasitism: One benefits, one is harmed (e.g., ticks on mammals). - Commensalism: One benefits, the other is unaffected (e.g., barnacles on whales). - Predation: One species hunts and eats another (e.g., lion and zebra). Competition: Species compete for the same resource (e.g., trees for sunlight).

Question 86

What is the source of energy for most ecosystems?

Answer 86

The Sun, providing energy for photosynthesis.

Question 87

How is energy transferred in an ecosystem?

Answer 87

- Producers (autotrophs) convert sunlight into chemical energy via photosynthesis. - Consumers (heterotrophs) eat other organisms to gain energy. - Decomposers (saprotrophs & detritivores) break down dead organic material.

Question 88

What is the difference between a food chain and a food web?

Answer 88

- Food chain: A single pathway of energy transfer. - Food web: Interconnected food chains showing complex feeding relationships.

Question 89

Why is only 10% of energy transferred between trophic levels?

Answer 89

Energy is lost as: Heat (respiration), movement, excretion (waste), and when not all parts of the organism are eaten or digested.

Question 90

Why are food chains typically only 4-5 trophic levels?

Answer 90

Because energy is lost at each level, higher levels don’t receive enough energy to support more trophic levels.

Question 91

What are the main processes in the carbon cycle?

Answer 91

- Photosynthesis: Removes CO₂ from atmosphere, converts to glucose. - Respiration: Releases CO₂ by breaking down glucose. - Decomposition: Dead organisms decompose, returning carbon to soil and air. - Combustion: Burning fossil fuels releases CO₂. Diffusion: CO₂ dissolves in and out of water bodies.

Question 92

How does human activity affect the carbon cycle?

Answer 92

- Burning fossil fuels increases CO₂. - Deforestation reduces photosynthesis, increasing atmospheric CO₂.

Question 93

How is carbon stored in ecosystems?

Answer 93

- Atmosphere: CO₂ gas. - Oceans: Dissolved CO₂ and carbonate ions in shells/coral reefs. - Fossil fuels: Coal, oil, natural gas (formed from decayed organisms).

Question 94

What is a carbon sink?

Answer 94

A natural reservoir that absorbs more CO₂ than it releases (e.g., forests, oceans).

Question 95

What are greenhouse gases?

Answer 95

Gases that trap heat in the atmosphere, causing the greenhouse effect.

Question 96

What are the most significant greenhouse gases?

Answer 96

- Carbon dioxide (CO₂): From combustion, deforestation. - Methane (CH₄): From livestock, rice paddies, landfill decomposition. - Water vapor (H₂O): Natural, but increases with warming. - Nitrous oxide (N₂O): From fertilizers, vehicle emissions.

Question 97

How does the greenhouse effect work?

Answer 97

- Sunlight (shortwave radiation) enters the atmosphere. - Earth absorbs energy and re-emits infrared radiation (longwave). - Greenhouse gases trap heat, keeping the planet warm.

Question 98

What are the consequences of climate change?

Answer 98

- Rising sea levels (due to melting glaciers). - More extreme weather patterns (storms, droughts). - Loss of biodiversity (species extinction). - Ocean acidification (CO₂ dissolves in water, harming marine life).

Question 99

What are the two types of autotrophic nutrition?

Answer 99

- Photoautotrophs: Use light (e.g., plants, algae). - Chemoautotrophs: Use inorganic chemical reactions (e.g., deep-sea bacteria).

Question 100

What is eutrophication, and what causes it?

Answer 100

- Excess nutrients (nitrates/phosphates) enter water bodies (from fertilizers, sewage). - Causes algal blooms, blocking sunlight → Oxygen depletion → Fish death.

Question 101

Why is biodiversity important?

Answer 101

Ensures ecosystem stability and resilience. Provides resources for medicine, agriculture.

Question 102

What are strategies for conservation?

Answer 102

- In situ conservation: Protecting species in their natural habitat (e.g., national parks). - Ex situ conservation: Protecting species outside their habitat (e.g., zoos, seed banks).

Question 103

What are alien species, and why are they a problem?

Answer 103

Non-native species introduced to an ecosystem, which may outcompete native species (e.g., cane toads in Australia).

Question 104

What is evolution?

Answer 104

A change in heritable characteristics of a population over time due to natural selection and genetic variation.

Question 105

What evidence supports evolution?

Answer 105

- Fossil Record: Older fossils show simpler organisms, newer fossils show more complex organisms. (Ex. Archaeopteryx [transition between dinosaurs and birds]) - Homologous Structures: Similar structures with different functions suggest common ancestry. (Ex. Pentadactyl limb in vertebrates.) - Selective Breeding: Humans breed animals for desired traits, showing rapid evolution. (Ex. Dog breeds from wolves.) - Comparative DNA: Similar DNA sequences suggest shared ancestry. (Ex. Humans and chimpanzees share ~98% DNA.) - Vestigial Structures: Reduced structures with no function, remnants of ancestral use. (Ex. Human tailbone, whale pelvic bones.)

Question 106

What are transitional fossils?

Answer 106

Fossils that show intermediate forms between ancestral and modern species (e.g., Tiktaalik, a link between fish and amphibians).

Question 107

What is adaptive radiation?

Answer 107

A single species evolves into multiple species to occupy different niches (e.g., Darwin’s finches in the Galápagos).

Question 108

What are the steps of natural selection?

Answer 108

- Overproduction of offspring – More offspring are born than can survive. - Genetic variation – Mutations, meiosis, and sexual reproduction create diversity. - Competition – Limited resources cause a struggle for survival. - Differential survival and reproduction – Individuals with advantageous traits survive and reproduce more. - Inheritance of favorable traits – Beneficial traits become more common over generations.

Question 109

What are the three sources of genetic variation?

Answer 109

- Mutation: New alleles arise from changes in DNA. - Meiosis: Crossing over and independent assortment shuffle genes. - Sexual reproduction: Combines genes from two parents.

Question 110

What is the function of the digestive system?

Answer 110

To break down food into smaller molecules that can be absorbed and used by the body.

Question 111

What are the main organs of the digestive system and their functions?

Answer 111

- Mouth: Mechanical digestion (chewing), chemical digestion (salivary amylase breaks down starch). - Esophagus: Moves food to the stomach via peristalsis. - Stomach: Acidic environment (pH 2) kills pathogens, pepsin digests proteins. - Small Intestine: Most digestion and nutrient absorption occurs here. - Pancreas: Secretes digestive enzymes (amylase, lipase, protease). - Liver: Produces bile, which emulsifies fats. - Gallbladder: Stores and releases bile. Large Intestine: Absorbs water, forms feces.

Question 112

What is peristalsis?

Answer 112

Wave-like contractions of smooth muscle that push food through the digestive tract.

Question 113

What enzymes are involved in digestion?

Answer 113

- Amylase: Salivary glands and the pancreas produce amylase. Starch (substrate) + Amylase (Enzyme) = Maltose (Product) - Protease (pepsin): The stomach produces protease. Proteins (substrate) + Protease (Enzymes) = Peptides (Product) - Lipase: Pancreas produces lipase. Lipids (substrate) + Lipase (Enzymes) = Glycerol + Fatty acids (Product)

Question 114

How are nutrients absorbed in the small intestine?

Answer 114

- Villi increase surface area for absorption. - Microvilli further increase surface area. - Nutrients pass into capillaries via diffusion, active transport, or facilitated diffusion.

Question 115

What are the components of blood?

Answer 115

- Plasma: Transports nutrients, hormones, and waste. - Red blood cells: Carry oxygen (hemoglobin). - White blood cells: Fight infections (immune response). - Platelets: Help in blood clotting.

Question 116

What are the types of blood vessels and their functions?

Answer 116

- Arteries: Carry blood away from the heart. They have thick muscular walls, high pressure - Veins: Carry blood toward the heart. They have thin walls, contain valves - Capillaries: Exchange of gases and nutrients. They have one-cell-thick walls

Question 117

What are the chambers of the heart?

Answer 117

- Right atrium: Receives deoxygenated blood from the body. - Right ventricle: Pumps deoxygenated blood to the lungs. - Left atrium: Receives oxygenated blood from the lungs. - Left ventricle: Pumps oxygenated blood to the body.

Question 118

What controls the heartbeat?

Answer 118

The sinoatrial (SA) node (pacemaker) sends electrical impulses to stimulate contraction.

Question 119

What are the two types of circulation?

Answer 119

- Pulmonary circulation: Blood to and from the lungs. - Systemic circulation: Blood to and from the body.

Question 120

What are pathogens?

Answer 120

Microorganisms that cause disease (e.g., bacteria, viruses, fungi, protozoa).

Question 121

What are the body's primary defenses against infection?

Answer 121

- Skin: Barrier against pathogens. - Mucous membranes: Trap pathogens in airways.

Question 122

How do phagocytes fight infections?

Answer 122

They engulf and digest pathogens via phagocytosis.

Question 123

What is the role of lymphocytes in the immune response?

Answer 123

- B cells produce antibodies. - T cells destroy infected cells.

Question 124

What is the difference between antibiotics and antivirals?

Answer 124

- Antibiotics: Kill bacteria by targeting cell walls, ribosomes, or enzymes. - Antivirals: Slow down virus replication.

Question 125

Why don’t antibiotics work on viruses?

Answer 125

Viruses lack cell walls, ribosomes, and metabolic pathways, so antibiotics have no effect.

Question 126

What is the function of the respiratory system?

Answer 126

To exchange oxygen and carbon dioxide between the lungs and blood.

Question 127

How does gas exchange occur in the alveoli?

Answer 127

- Oxygen diffuses into blood (capillaries). - Carbon dioxide diffuses out into the alveoli to be exhaled.

Question 128

What are the adaptations of alveoli for gas exchange?

Answer 128

- Large surface area - Thin walls (one-cell thick) - Moist lining for gas diffusion - Rich blood supply (capillaries)

Question 129

What muscles control breathing?

Answer 129

- Inhalation: Diaphragm contracts, ribcage moves up. - Exhalation: Diaphragm relaxes, ribcage moves down.

Question 130

What is the function of neurons?

Answer 130

To transmit electrical impulses throughout the body.

Question 131

What are the three types of neurons?

Answer 131

- Sensory neurons – Carry signals to the CNS. - Motor neurons – Carry signals from the CNS to muscles. - Interneurons – Connect neurons in the CNS.

Question 132

How do neurons transmit signals?

Answer 132

- Resting potential: Neuron at rest (-70mV). - Action potential: Sodium (Na⁺) enters, causing depolarization. - Repolarization: Potassium (K⁺) exits, restoring charge.

Question 133

What happens at a synapse?

Answer 133

1. Electrical signal reaches the axon terminal. 2. Neurotransmitters (e.g., acetylcholine) are released. 3. They cross the synaptic gap and bind to receptors. 4. A new signal is triggered in the next neuron.

Question 134

What is homeostasis?

Answer 134

Maintaining a stable internal environment (e.g., body temperature, blood glucose).

Question 135

How does the body regulate blood glucose levels?

Answer 135

- Insulin (from pancreas): Lowers blood sugar by storing glucose as glycogen. - Glucagon (from pancreas): Raises blood sugar by converting glycogen to glucose.

Question 136

What hormones control the menstrual cycle?

Answer 136

- FSH (Follicle-stimulating hormone) – Stimulates follicle growth. - LH (Luteinizing hormone) – Causes ovulation. - Estrogen – Thickens the uterine lining. Progesterone – Maintains uterine lining.

Question 136

What are the stages of fertilization?

Answer 136

1. Sperm reaches the egg. 2. Acrosome reaction allows sperm to penetrate. 3. Egg membrane changes to prevent other sperm from entering. 4. Zygote forms.