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SBI4U exam review
Exam review for grade 12 university biology
| Question | Answer |
|---|---|
| What is an enzyme? | A biological macromolecule that catalyzes, or speeds up a chemical reaction in biological systems. |
| What is ATP? | Adenosine Triphosphate (Adenine + Ribose + 3 Phosphate), energy is stored in the bonds between the phosphates. |
| What is Glycolysis? | A metabolic pathway that breaks glucose down to pyruvate. |
| What is a Chloroplast? | An organelle in the cells of photosynthetic organisms, in which light from the sun is captured and stored in the form of high-energy organic molecules such as glucose. |
| What is Photosynthesis? | The process by which carbon dioxide, water and certain inorganic salts are converted into carbohydrates by green plants using energy from the sun. |
| What is Hydrolysis? | A chemical reaction that results in cleavage of a covalent bond whereby a hydrogen atom is attached to one atom in the bond and a hydroxyl group is added to the other atom of the bond with addition of a water molecule. |
| What is an Anticodon? | A triplet of bases positioned at one end of a tRNA, which recognizes and base pairs with a codon on mRNA during protein synthesis. |
| What is Splicing? | In mRNA, a process of excising out the introns and combining in the exons. |
| What were Hershey and Chase's contribution to genetics? | Found that the genetic information transferred form virus to bacteria was only possible as a result of DNA being injected into bacteria cells. They performed blender experiments. |
| What did Hershey and Chase discover in the blender experiments? | 1) Viruses with radioactively labeled DNA and a normal protein coat. 2) Viruses without radioactive DNA, but had a radioactive protein coat. |
| What were Watson and Crick's contribution to genetics? | Produced a structural model of DNA double helix, found that the two strands run in opposite directions and are not identical. |
| what was Franklin's contribution to genetics? | Found that DNA had a helical structure, that nitrogenous bases were located on the inside of the molecule and that sugars and phosphates were on the outside. |
| What was Chargaff's contribution to genetics? | He discovered that the 4 nucleotides in DNA aren't present in equal amounts and nucleotide compositions varies for different species C=G, T=A. |
| DNA vs. RNA | Transcription is synthesis of RNA and form a DNA template while DNA replication is the process in which two identical DNA molecules are produced from an original parent molecule. |
| What are the enzymes involved in DNA replication and what do they do? | Helicase unwinds, primase makes RNA primer that makes Okazaki fragments, SSB stabilizes DNA when it unwinds, topoisomerase relieves strain from unwinding, DNA polymerase 123 add nucleotides, remove primer and proof read, DNA Ligase binds new strands. |
| What are chemical mutagens? | Molecules that can enter the nucleus of a cell and induce mutations by reacting with DNA. Some have a similar structure to DNA and can incorporate into a DNA strand and cause incorrect base pairing during replication (nitrates/cigarette smoke chemicals) |
| What are physical mutagens? | An event or substance such as a high energy radiation. These mutagens physically change the structure of DNA such as distortion (UV or Xrays). |
| What is Point Mutation? | Is a mutation involving a single base pair substitution, insertion or deletion. |
| What is Frameshift Mutation? | A mutation caused by the addition or deletion of a number of nucleotides not divisible by 3 resulting in a change in the reading frame. |
| What is Substitution? | They do not affect neighbouring coding sequences. |
| What is Non-sense Mutation? | A mutation that shortens a protein by introducing a stop codon. |
| What is a Mis-sense Mutation? | A mutation that changes the amino acid sequence of a protein. |
| What is Silent Mutation? | A mutation that doesn't change the amino acid sequence of a protein. |
| What is Positive Feedback? | A mechanism of homeostatic response by which the output of a system strengths or increases a change in homeostasis. |
| What is Negative Feedback? | A mechanism of homeostatic response by which the output of a system reverses a change in variable, bringing the variable back to within normal range. |
| What is the body's response to cold? | Shivering, negative feedback system, sensors in the skin and brain send messages to the control center, which sends messages to several effectors. Blood vessels in the skin constrict, decreasing heat loss through the skin. Metabolism increases makes heat. |
| What is a Nephron? | A microscopic tube-like filtration unit found in the kidneys that filters and reabsorbs various substances from the blood; produces urine. |
| What is Glomerular Filtration? | In the kidney the process that results in the movement of water and solutes, except proteins, from the blood plasma into the nephron down a pressure gradient. |
| What is Insulin? | A hormone secreted by the alpha cells if the islets of Langerhans in the pancreas to make target cells more permeable to glucose; enables the body to use sugar and other carbohydrates. |
| What is Glucagon? | A hormone produces by the alpha cells of the islets of Langerhans in the pancreas to stimulate the liver to convert glycogen back into glucose, which is released in the blood. |
| What is the Relax Arc? | A simple connection of neurons that result in a reflex action in response to a stimulus? |
| What is Resting Potential? | The potential difference across the membrane in a resting neuron. |
| What is the all or none principle? | The principle that that governs the responses of an axon to a stimulus; if a neuron is stimulated sufficiently an impulse will travel the length of the axon, but if the stimulus is not sufficient no impulse will travel down the axon. |
| What are the parts of the central nervous system? | The brain, the spinal cord. |
| What are the parts of the Peripheral Nervous System? | -Autonomic relays info to internal organs (sympathetic, controls organs in stress, flight or fight reaction) -Somatic relays info to and from skin and skeletal system (sensory nerves, motor nerves) |
| What is active transport? | the process of moving materials backwards up their concentration gradient from high to low concentration. |
| What is Facilitated Diffusion (Passive Transport)? | The transport of ions or molecules across a membrane means of a membrane protein along the concentration gradient for that ion or molecule, used when materials are too large to diffuse across the membrane. |
| What is Anaerobic Respiration? | A form of cellular respiration that occurs in the absence of oxygen; molecules such as carbon dioxide, nitrate and sulfate are the final electron acceptors. |
| What is Aerobic Respiration? | Catabolic pathways that require oxygen. |
| What is the Endocrine System? | In vertebrates a system that works in parallel with the nervous system to maintain homeostasis by secreting hormones that serve as chemical messengers from various glands composed of hormone producing glands and tissues of the body. |
| What are Nucleic Acids? | a macromolecule composed of nucleotide monomers. |
| What is Osmosis? | The diffusion of water across a membrane form an area of high concentration of water molecules to an area of lower concentration of water molecules. |
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ruyguy96