SCI 3RD QA PDF Past Paper

1. Surface of the cerebrum with deep, wrinkle grooves Spinal Cord: * cerebral cortex The spinal cord acts as a highway for information traveling between 2. A nerve fiber that connects the left and right cerebral hemispheres...

1. Surface of the cerebrum with deep, wrinkle grooves Spinal Cord: * cerebral cortex The spinal cord acts as a highway for information traveling between 2. A nerve fiber that connects the left and right cerebral hemispheres the brain and the body. It sends instructions from the brain to the of the brain * corpus callosum body and carries sensory information back to the brain. lt also coordinates reflexes, which are fast, automatic responses to stimuli. ----------------------THE NERVOUS SYSTEM The Nervous System controls and interprets all the activities that PERIPHERAL NERVOUS SYSTEM (PNS) happen in the body. The PNS has two main divisions: It makes the body respond quickly to changes in the environment by accomplishing four basic functions. Somatic Nervous System: «Gathers information both from the outside world and from inside the Controls voluntary movements of the muscles and sends sensory body information to the CNS. «Sends information to muscles, glands, and organs so they can respond quickly Autonomic Nervous System: «Transmits information to the processing areas in the brain and Regulates involuntary functions like heart rate, digestion, and spinal cord breathing. «Processes information to determine the best response AUTONOMIC SYSTEM: SYMPATHETIC & PARASYMPATHETIC NEURONS The Autonomic Nervous System is divided into two parts: «Neurons are the basic functional units of structure and function of the Nervous System. Sympathetic Nervous System: «They carry information through the nervous system in the form of Prepares the body for stressful or emergency situations, also known nerve impulses. as the "fight or flight" response. It increases heart rate, widens «Nerve Impulse is a wave of chemical and electrical signal that is airways, and slows down digestion to give the body more energy and conducted along membrane of a neuron focus in dangerous or stressful moments. PARTS OF NEURONS Parasympathetic Nervous System: Dendrites Helps the body relax and recover after stress. This is called the "rest - These tree-like extensions receive information from other neurons and digest" response. It slows the heart rate, promotes digestion, and and transmit electrical stimulation to the cell body. Dendrites are helps the body conserve energy. covered with synapses, which are the junctions between neurons that allow signals to pass between them. ----------------------NEUROLOGICAL DISORDER Axon CEREBRAL PALSY - This long, tube-like cable carries electrical impulses away from the a disorder resulting in a lack of full control of physical movement and cell body to be received by other neurons. muscle tightness that affect almost all parts of the body. Cell body PARKINSON’S DISEASE -Also known as the soma, this is the central part of the neuron that a disorder of the nervous system that affects the movement of a includes the nucleus. person. It develops gradually and tremors start in the hands. BRAIN TUMOR TWO MAIN PARTS OF THE NERVOUS SYSTEM It is formed in the meninges that cover the brain and the spinal cord. The Central Nervous System CNS is like the command center of the EPILEPSY body. It processes information and controls all the activities in your clusters of nerve cells or neurons act abnormally. The action potential body, both voluntary like moving your hand and involuntary like activity becomes disturbed causing strange sensations and emotions, breathing. The CNS is made up of two main parts: the brain and the convulsions, and muscle spasms. spinal cord. ALZHEIMER’S DISEASE condition characterized by severe mental deterioration which gets The Peripheral Nervous System PNS is made up of all the nerves worse over time — can lead to decrease in brain size that are outside the CNS. These nerves branch out from the brain and spinal cord and reach all parts of your body like a network of ----------------------INFECTIONS OF THE NERVOUS SYSTEM telephone lines connecting every area to the main control center. The ENCEPHALITIS PNS connects your body to the CNS and plays a crucial role in acute infection and inflammation of the brain. The infection commonly sending and receiving signals affects children, the elderly, and those with weak immune systems. MENINGITIS CENTRAL NERVOUS SYSTEM (CNS) inflammation of the meninges and the membranes surrounding the The CNS is made up of the brain and spinal cord brain and the spinal cord. Brain: RABIES The brain is the control center for the entire body. It processes viral infection transmitted through bites by infected animals such as sensory information, thoughts, emotions, and controls body functions dogs and cats. The rabies virus can spread From the point of the bite like movement. The brain is divided into different regions that handle area, specifically from the muscles, then to nearby nerves, and the specific tasks. brain. > Cerebrum TETANUS largest part of the brain disease caused by certain bacteria found in the soil contaminated Two hemispheres - left and right with animal waste > Cerebellum coordinates the actions of the muscles and maintains the balance so that the motor movements of the body can move smoothly, steadily, and efficiently. > Brain Stem coordinates to many survival functions of the body such as breathing, heart rate, sleep, and wakefulness. 1. Blood circulates through the body to carry oxygen to different organs. True THE NERVOUS SYSTEM 2. Glands are part of the digestive system only. False The nervous system controls fast responses, like moving your hand 3. The body needs energy from food to function properly. True away from hot objects. It includes the brain, spinal cord, and nerves. 4. Sweating helps cool the body down when it gets too hot. True It uses electrical signals to respond quickly to changes. 5. Breathing is controlled by muscles and the lungs. True Example: Touching a hot surface triggers nerves to send a quick signal to your brain, which makes you pull your hand back. ------------------HORMONAL CONTROL AND COORDINATION The endocrine system is a network of glands that produce and RECEPTORS, COORDINATION CENTRES, AND EFFECTORS release hormones. Control systems involve: Hormones are chemical messengers that travel through the Receptors: Detect changes in the environment (stimuli). bloodstream to organs and tissues, telling them how to function. Control Center: The brain or spinal cord process the information. Effectors: Muscles or glands that make the necessary adjustments. FUNCTION OF HORMONE Example: When it's too hot, receptors in the skin detect the heat, the regulating growth, development, behavior, and reproduction brain processes it, and sweat glands (effectors) help cool you down. coordinating the production, use and storage of energy maintaining internal homeostasis such as nutrition, excretion, water, —------FEEDBACK MECHANISM IN HORMONAL CONTROL and salt balance reacting to stimuli from outside the body Positive Feedback –an increased hormone secretion is enhanced to produce even more WHAT ARE GLANDS? hormone Glands are special organs in the body that produce and release Negative Feedback substances, such as hormones. –counteracts the production of more hormones; decreases the Glands in the endocrine system release hormones directly into the deviation of the hormone level from the normal value. bloodstream, allowing them to travel to the organs that need them. Major glands in the body include the pituitary gland, thyroid, adrenal a. During childbirth, more hormones are released to stimulate the glands, and pancreas. contraction of the uterus, which enables the mother to release the baby b. The rise of glucose in the blood triggers the production of insulin HYPOTHALAMUS connects your endocrine system with your nervous system. Its main job is to NEGATIVE FEEDBACK IN HORMONAL CONTROL tell your pituitary gland to start or stop making hormones. The body uses feedback systems to keep hormone levels balanced. PITUITARY GLAND For example, when blood sugar gets too high, the pancreas releases master gland. It uses information it gets from your brain to tell other glands in your body what to do. insulin to lower it. When blood sugar gets too low, the pancreas THYROID GLAND releases glucagon, which tells the liver to release stored sugar, makes thyroid hormone, which controls your metabolism. raising blood sugar levels. PARATHYROID controls the amount of calcium in the body POSITIVE FEEDBACK IN HORMONAL CONTROL THYMUS Childbirth makes white blood cells called T Lymphocytes that fight infection and are During Labor, a hormone called oxytocin is released that intensifies crucial as a child's immune system develops. The thymus starts to shrink after and speeds up contractions. The increase in contraction causes more puberty ADRENALS oxytocin to be released and cycle goes on until the baby is born best known for making the "fight or flight" hormone; gives strength and power to your muscles during emergency situations. HOMEOSTASIS AND BLOOD SUGAR PANCREAS One important function of homeostasis is controlling blood sugar part of both your digestive and endocrine systems. It makes digestive levels. The hormone insulin, produced by the pancreas, helps lower enzymes that break down food. These ensure you have the right amount of blood sugar when it's too high. Another hormone, glucagon, raises sugar in your bloodstream and your cells blood sugar when it's too low. OVARIES Example: After eating, insulin helps cells absorb glucose from the develop breasts at puberty, regulate the menstrual cycle, and support a pregnancy. bloodstream. TESTES It helps them grow facial and body hair at puberty. It also tells the penis to ----------------------ENDOCRINE DISORDERS grow larger and plays a role in making sperm. HYPOTHALAMIC DISEASE PINEAL GLAND disease in hypothalamus helps your body get ready to go to sleep KALLMANN SYNDROME is due to deficiency of gonadotropin releasing hormone (GnRH). HOMEOSTASIS Kallmann syndrome is a type of hypogonadotropic hypogonadism, Our bodies are like machines that need everything to work just right. which is a condition where the body doesn't produce enough For example, cells need a specific temperature, enough water, and hormones for sexual development the right amount of glucose (sugar) to survive.To help with this, our DWARFISM body uses control systems to monitor these things and make a condition in which the pituitary gland does not make enough growth adjustments when needed. hormone which may lead to slower growth Categories of Dwarfism: i. Proportionate - body parts are in proportion but shortened Homeostasis is the process that keeps conditions inside the body ii. Disproportionate - an average-size torso and shorter arms and legs steady, even when things change outside. These control systems rely or a shortened trunk with longer limbs on two important networks: GIGANTISM 1. The nervous system (which works fast) a condition in which pituitary gland produces too much hormone 2. The hormonal system (which usually works slower). which may cause abnormal growth to children ACROMEGALY THE HORMONAL SYSTEM a hormonal disorder that develops when your pituitary gland The hormonal system controls slower responses, like growth or produces too much growth hormone during adulthood changes in your body during puberty. Hormones are chemicals CUSHING SYNDROME released by glands and travel through the bloodstream to target occurs when your body is exposed to high levels of the hormone organs. Example: Hormones regulate the menstrual cycle and blood cortisol for a long time sugar levels. ----------------------THE ADRENAL GLANDS AND STRESS TRANSCRIPTION The adrenal glands release hormones like adrenaline and cortisol in a certain portion of the DNA is transcribed into the RNA response to stress. These hormones prepare the body for a “fight or antisense strand or template strand – strand that is transcribed into flight” reaction by increasing heart rate, boosting energy, and making you more alert. RNA sense strand or coding strand – “non template” DNA strand Cortisol also helps the body manage long term stress by controlling starts at 5’ to 3’ direction relative to the RNA strand blood sugar levels and reducing inflammation. RNA polymerase develops RNA nucleotide starting from the promoter region. Promoter region signals the RNA polymerase to Adrenal Glands: Glands above the kidneys that produce hormones to manage stress. start transcription. Ends when it detects terminators – sequence that Endocrine System: A network of glands that produce hormones to control certain body functions. Feedback System: A process where the body maintains balance by adjusting hormone levels. signals the end of the transcription. RNA will be mRNA that will be Glucagon: A hormone released by the pancreas that raises blood sugar levels when they are too low. processed. 20 amino acid; 64 codons Glands: Special organs that produce and release substances like hormones. Hormones: Chemical messengers produced by glands that regulate body functions. Insulin: A hormone produced by the pancreas that lowers blood sugar by helping cells absorb sugar. CODONS – the genetic code transcribed in the mRNA uses a set of Pancreas: A gland that controls blood sugar by releasing insulin and glucagon. Thyroid Gland: A gland in the neck that produces hormones controlling metabolism. three nucleotide bases to specify an amino acid – the building block of protein —--------------------PROTEIN SYNTHESIS TRANSLATION The molecular components of DNA: (RNA to Protein) phosphates, deoxyribose (a sugar), and the four nitrogenous bases, Polypeptide – chain of amino acid linked together by a peptide bond adenine, guanine, cytosine, and thymine. A processed and packaged polypeptide forms a protein Base pairing as: Adenine - Thymine Cytosine - Guanine tRNA interprets the information transcribed in the mRNA there are many types of tRNA, each carries specific amino acid into DNA STRUCTURE the ribosome RNA is a polymer with a ribose and phosphate backbone and with tRNA has a set of three nucleotide bases, called anticodon, on one of four different bases: adenine, guanine, cytosine, and Thymine(T). its end that specifically pair with the mRNA codons RNA STRUCTURE the exact pairing of codon and anticodon ensures that the correct RNA is a polymer with a ribose and phosphate backbone and with amino acid is delivered into the ribosome four different bases: adenine, guanine, cytosine, and uracil (U). INITIATION NUCLEOTIDES 5’ end of mRNA attaches to the ribosome Then, mRNA starts with Phosphate group/ Pentose sugar/ Nitrogenous bases the start codon AUG AUG codes for methionine Purines (adenine and guanine) are two-carbon nitrogen ring bases Transfer RNA that carries methionine the bind to the ribosomes Pyrimidines (cytosine and thymine) are one-carbon nitrogen ring bases. ELONGATION Other amino acid are added to methionine PROTEINS Each amino acid is linked by peptide bond the cell’s molecular workers that directly affects its function and tRNA continuously deliver amino acids dictated by the codons in the reproduction They also control the synthesis of other molecules like RNA lipids, carbohydrate and nucleic acids Proteins are synthesized in structures called ribosomes that are TERMINATION located outside of the nucleus happens when the ribosome meet a stop codon The molecular instruction on how to create a protein must travel from UGA, UAA, and UAG the DNA to the Cytoplasm After the process of termination, the polypeptide chain is processed The ribonucleic acid (RNA) mediate the transfer of information by endoplasmic reticulum to make protein DEOXYRIBONUCLEIC ACID (DNA) Molecular blueprint of life —---------------------MUTATIONS ON CHANGING controls the cell’s internal function and dictates the organism’s STRUCTURES AND FUNCTION OF PROTEIN physical characteristics. The genetic information contained in the A gene is a section of DNA (genetic code).Our genetic code is a DNA is also hereditary and transferable. It also instructs the creation blueprint for our bodies. Just like how different LEGO blocks can of protein in the cell. The information, in the form of genetic codes, create different structures, our DNA determines how our bodies are inside the DNA are translated to form proteins built and function. RIBONUCLEIC ACID (RNA) A genetic mutation is a change that occurs of nucleotide bases within is a single strand molecular structure similar to DNA a certain part of the DNA The four nucleotides are: TWO PROCESS OF PROTEIN SYNTHESIS Adenine (A) Cytosine (C) Guanine (G) Thymine (T) Transcription Sometimes, mistakes happen during the DNA copying process, DNA to RNA leading to changes called mutations. synthesizes special type of RNA called messenger RNA (mRNA) transfer information from DNA into mRNA WHAT CAUSES MUTATIONS? happens in the nucleus for eukaryotes and in the cytoplasm for mutations are changes that occur naturally prokaryotes mistakes during the replication process of the DNA happen often but are most of the time corrected immediately by proofreading enzymes Translation failure to correct errors usually results to defective genes RNA to Protein can also be induced by certain physical and chemical agents called mRNA molecule detached from the DNA and binds with the ribosome Mutagens. to start protein synthesis It happens in the cytoplasm EFFECT OF MUTATION usually has a detrimental effect on the cell by affecting the proper Changes in the population happen gradually. Changes are inherited function of the genes, which causes gene products to be defective through generation there are some cases when mutation is neutral, with no evident effect Natural Selection on the organism Variation exists in the population and those that have the ability to in rare cases, can be beneficial to the organism by introducing new survive exist and reproduce. gene products that can enhance cellular functions What pieces of evidence show that evolution happened? CLASSIFICATION OF MUTATIONS 1. FOSSILS Fossils are the preserved remains of ancient organisms —NUCLEOTIDE SUBSTITUTION They can form from hard body parts (bones, shells) that resist decay caused by the failure of DNA’s proofreading enzyme to properly or are replaced by minerals. Traces like footprints and burrows can correct a base pairing error also fossilize when covered by sediment. Soft-bodied fossils are rare happens when individual nucleotide bases, along with its due to decomposition, but they provide valuable insights. complementary base, are wrongfully replaced with another pair. For We can compare and contrast fossils with existing animals/plants to example, a G (guanine) might be swapped for a C (cytosine). identify changes that happen through time. Fossil layer is a layer of the least detrimental among the type of point mutation. minor or no fossils developed along with sedimentary rock effect at all on gene products fossils at the deepest part are very different from modern organisms. Silent mutation - a change in base sequence encoded for the same the youngest fossils have more resemble to modern organism amino acid that the original replaced gene would produce Fossil records provided evidence that not all organisms were created —INSERTION MUTATIONS at the same time but existed in different periods through evolution. refers to the change in DNA base sequence due to addition of one or Similarity of extinct and living Fossils of trilobite, an extinct organism more nucleotide base into a gene group of joint-legged animals —DELETION MUTATION refers to the change in DNA base sequence when the gene loses one 2. ANATOMY OF SPECIES or more nucleotide base pair study the similarities and differences in the body structure of different organisms. shows the different species can be linked with common INSERTION AND DELETION MUTATION ancestors. Studying the presence of homologous structures in has a more serious effect on the gene products. anatomy provides evidence for evolution. Homologous structures are are usually detrimental to cells by modifying the DNA sequence to the anatomical features in different species with similar structures but extent that the gene's protein products become useless or have other may have varying functions, indicating a common ancestry. unintended effects. another common outcome is the premature stop of the polypeptide production, which produce non-functioning proteins 3. MOLECULAR BIOLOGY that are immediately destroyed not included in Darwin’s theory. Proposed by Gregor Mendel. provides evidence for evolution by comparing DNA sequences, Some mutations do not cause any noticeable changes, while others protein folds and other molecular attributes can lead to genetic disorders or diseases. shows that all organisms have approximately the same biochemical Mutations can even give an organism an advantage in its traits. all organisms came from a common ancestor and inherited the environment, leading to new traits or abilities (species evolution). same complex biochemical trait SICKLE CELL ANEMIA EXPLORING THE OCCURENCE OF EVOLUTION The disease is caused by a mutation in the gene that helps make Organisms tend to produce offspring than needed to replace the hemoglobin — a protein that carries oxygen in red blood cells. It is a parent generation Population of a species remain relatively constant point mutation where A (adenine) is replaced by a U (Uracil). in size despite the fact that organism tend to produce more offspring Individuals in a natural population vary from each other. Some of —-----------THE EVIDENCE FOR EVOLUTION them will have advantageous traits that can help them endure PIONEERS IN THE STUDY OF EVOLUTION environmental stresses (e.g. having greater ability in obtaining food Charles Darwin (1809-1882) and resources, escaping predators and preys) He developed the theory of evolution by natural selection. On the Variation in traits can be passed on by parents to their offspring. Origin of Species in 1859. Some of these varying traits might affect the species survival and Alfred Wallace (1823-1913) reproduction. He also independently developed the theory of evolution through natural selection. Wallace conducted his study in the Malay NATURAL SELECTION Archipelago These observations suggest that evolution works by natural selection. Organisms compete with each other in order to survive and be able DARWIN’S THEORY to produce more offspring. Variations in traits among organisms can Darwin’s theory of natural selection can be summarised as follows: give rise to favorable characteristics that enable organisms to have Within a species, individual organisms exhibit a wide range of advantages among others, like better ability to find food and variation for specific characteristics. Those individuals with traits best resources. Variations among organisms help determine which suited to their environment have a higher chance of surviving and individual has the better ability to survive and reproduce. Natural reproducing. selection is a natural phenomenon that acts on every organism of a Over time, these advantageous characteristics are passed on to the species, where an individual with a certain advantageous inherited next generation, driving evolution through natural selection. trait is able to produce more offspring than other organisms in the population without that certain trait. Natural selection is capable of THEORY OF EVOLUTION contentiously affecting subsequent generations over a long period of Evolution happens over a long period of time and species exist from time, where beneficial traits accumulate and are inherited by a large time to time proportion of the population. When a population migrates or is Common Descent introduced into a new environment, natural selection over time can all species have originated from a single or a group of common push these individuals to develop adaptations. This process, in ancestors that have diversified through time certain cases, leads to a creation of a whole new species. Natural Species Multiply selection will always act on organisms. Traits that will be favored by New species exist due to the divergence of existing ones the process will be dependent on the environment and other external Gradualism factors. EVOLUTION Water Cycle Favorable traits cannot be predicted because variations among * use water properly and appropriately organisms are purely random. This is because mutations in our DNA * conserve water happen purely by chance. Organisms that were determined to be * do not pollute bodies of water more fit to survive can pass their advantageous traits to a larger number of individuals in the population in the following generations by Carbon Cycle leaving more offspring. Evolution acts on the whole population. * do not burn plastics, wastes, and other materials * plant trees Explaining How Species Diversity Increases the Probability of * minimize the use of fossil fuels Adaptation and Survival of Organisms in Changing Environments Nitrogen and Phosphorus Cycle Species Diversity * limit the use of inorganic fertilizers large variation in traits increases the chance that some individual in * promote organic agriculture the population will survive the change in environment diversity will ensure that not all members of the species will be Biodiversity Loss susceptible to the same environmental stress * plant trees * protect and conserve habitats Adaptation and Survival * prevent illegal poaching Adaptation is necessary for the species to increase their survival * do not introduce invasive species capabilities during conditions where there is a change in the environment. Disruption of Biogeochemical Cycles Water Cycle: Problems Changing the environment can reduce population size that may even > water pollution makes water non-usable by most organisms cause extinction. On the other hand, environmental changes may > lack of water conservation causes too much depletion of become the grounds for species to develop new or modify old underground water characteristics for survival. > atmospheric pollution causes acid rain Individuals within a population have varying traits. Some of these Water Cycle: Solutions traits can be good, bad, or neutral to the individual organism based > avoid throwing garbage or wastewater on bodies of water on environmental conditions. > use water properly and if needed only > know and understand the water cycle A trait variation that can give advantage to the organism to survive and reproduce, within a particular environment, usually accumulates Carbon Cycle: Problems in the population over time. This advantageous trait will give rise to > burning of fossil fuels, verhege, and other materials can increase adaptations. the amount of carbon dioxide in the air causing greenhouse effect and global warming Natural Selection and Diversity > deforestation or illegal logging can decrease the amount of carbon Natural Selection can alter species in three way: dioxide 1. Directional Selection — extreme variants of traits is favored in the environment. This usually happens when a population is introduced Carbon Cycle: Solutions into a new habitat. > avoid burning plastics and other materials 2. Disruptive Selection — both extreme variants of a trait is favored in > minimize the use of fossil fuels, instead, use bicycles and other the environment, leaving those with intermediate characteristics at environment-friendly vehicles disadvantage > plant and grow a tree 3. Stabilizing Selection — the intermediate variant of trait is favored over the two extreme variations Nitrogen and Phosphorus Cycle: Problems > too much use of inorganic fertilizers can affect the concentration of FOR EXAMPLE Fur color in a certain species of mouse Is a heritable nitrogen and phosphorus in land and bodies of water trait. This trait greatly varies among the population, from light gray to > too much nitrogen and phosphorus can cause eutrophication and dark brown. algal bloom SUMMARY Certain variation of traits among a species can be good, bad or The Outcome: Biodiversity Loss neutral to the individual organism based on environmental conditions. Problems: A beneficial variation of a trait, within a particular environment, > illegal poaching and illegal wildlife trade can threaten the different usually accumulates in the population over time giving rise to species in the wild adaptations. > introduction of invasive species can disrupt the food chain Adaptation equips organisms to better fit in their environment, > deforestation and illegal logging can destroy natural habitat improving their survival and reproduction capabilities. Large species diversity ensures that an advantageous variation of Solutions: trait in the population will be available in > plant more trees changing environments. > understand and recognize biodiversity through education and Species diversity ensures that not all members of the species will be communication susceptible to the same environmental stress. > contribute in the protection and conservation of forests and other ecosystems Explaining the Relationship between Population Growth and Carrying Capacity Suggesting Ways to Minimize Human Impact on the Environment Human Impact on the Environment Human activities can disrupt different biogeochemical cycles, thus, can increase biodiversity loss.