Biology 9 Quarter 1 PDF

BIOLOGY 9 QUARTER 1 S.Y. 2024-2025 **Summarized By: Abdulhalik, Alhamir H.** **Lesson 1.1 Respiratory System:** - The respiratory system is the system of the body that deals with breathing. When we breathe, the body takes in the oxygen that it needs and removes the carbon dioxide that...

BIOLOGY 9 QUARTER 1 S.Y. 2024-2025 **Summarized By: Abdulhalik, Alhamir H.** **Lesson 1.1 Respiratory System:** - The respiratory system is the system of the body that deals with breathing. When we breathe, the body takes in the oxygen that it needs and removes the carbon dioxide that it doesn't need. **Parts of the Respiratory System:** 1. **Nose**: The nose filters, warms, and humidifies incoming air while also serving as the primary entry point for inhalation. 2. **Mouth**: The mouth acts as an alternative airway for breathing, allowing for increased airflow during activities like exercise. 3. **Pharynx**: The pharynx serves as a passageway for air and food, connecting the nasal and oral cavities to the larynx and esophagus. 4. **Larynx**: The larynx houses the vocal cords and functions as a passageway for air between the pharynx and trachea, preventing food and liquids from entering the airway. 5. **Trachea**: The trachea is a tube that transports inhaled air from the larynx to the bronchi, lined with cilia to trap particles. 6. **Lungs**: The lungs are large, spongy organs that facilitate the exchange of oxygen and carbon dioxide between the air and the bloodstream. 7. **Bronchi**: The bronchi are two main branches from the trachea that carry air into each lung, further dividing into smaller passages. 8. **Bronchioles**: Bronchioles are small air passages within the lungs that branch from the bronchi and lead to the alveoli. 9. **Alveoli**: Alveoli are tiny air sacs in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be expelled. 10. **Diaphragm**: The diaphragm is a dome shaped muscle that contracts and relaxes to change the pressure in the chest cavity, enabling breathing. **Breathing: Inhalation and Exhalation:** - **Inhalation (inspiration)** is the process of drawing air into the lungs. During inhalation, the diaphragm contracts and moves downward, and the intercostal muscles between the ribs contract, expanding the chest cavity. This expansion reduces the pressure inside the thoracic cavity, causing air to flow into the lungs to equalize the pressure. - **Exhalation (expiration)** is the process of expelling air from the lungs. During exhalation, the diaphragm relaxes and moves upward, and the intercostal muscles relax, causing the chest cavity to decrease in volume. This increase in pressure within the thoracic cavity forces air out of the lungs. **Lesson 1.2 Circulatory System:** - It is the life support structure that nourishes your cells with nutrients from the food you eat and oxygen from the air you breathe. - It circulates vital elements such as oxygen and nutrients. - It also transports wastes away from the body. **Parts of the Circulatory System:** - The heart, blood, and blood vessels make up the Cardiovascular or circulatory system, which is responsible for distributing oxygen and nutrients to the body and carrying away carbon dioxide and other waste products. 1. **Heart** - Pumps the blood throughout the body. It has four chambers: two ventricles and two atria. - The upper chambers are the two atria. The atria are the receiving chambers of the heart, accepting blood from the body (Right Atrium) and the lungs (Left Atrium). - In the lower chamber are the two ventricles. The ventricles are the pumping chambers, moving blood to the lungs (Right Ventricle) and into the body (Left Ventricle). - Four valves within the heart prevent the blood from flowing backward in the heart chambers and out to the aorta. - It controls the flow of blood to and from the heart and lungs and through the body. 2. **Blood** **Vessels** - Carry the blood throughout the body. - **ARTERIES** - carry oxygenated blood away from the heart to the cells, tissues, and organs of the body. - **VEINS** - carry deoxygenated blood to the heart. - **CAPILLARIES** - the smallest blood vessels in the body, connecting the smallest arteries to the smallest veins. The actual site where gases and nutrients are exchanged. 3. **Blood** - carries the materials (oxygen and nutrients) throughout the body. **How blood flow through your heart:** 1. Blood from the lungs returns to the heart by entering the left atrium. 2. When the wall of the left atrium contracts, blood goes to the left ventricle. 3. When the wall of the left ventricle contracts, blood rushes to all parts of the body. 4. Blood flows in this direction and not backward because of the presence of the flaps of muscles (valves). 5. The valves are like one-way doors that keep the blood moving in one direction. 6. In humans, blood circulates through two pathways: pulmonary circulation and systemic circulation. 1. **PULMONARY CIRCULATION**: Movement of blood from the heart to the lungs, and back to the heart 2. **CORONARY CIRCULATION**: Movement of blood through the tissues of the heart 3. **SYSTEMIC CIRCULATION**: Movement of blood from the heart to the rest of the body, excluding **Lesson 1.3 Diseases Affecting the Respiratory and Circulatory Systems:** **Unhealthy Lifestyles:** 1. **Cigarette Smoking:** causes respiratory problems like coughing and wheezing and can lead to lung diseases like bronchitis, emphysema, pneumonia, and cancer. Respiratory problems arise because cigarettes contain tar and nicotine that make the gaseous exchange process inefficient. Tar deposits clog up the alveoli and nicotine cause the constriction of the blood vessels in the lungs slowing down the flow of the blood in the lungs. Smoking cigarettes can have many adverse effects on the body. Some of these can lead to life- threatening complications. Smoking cigarettes can damage the heart, blood vessels, and blood cells. The chemicals and tar in cigarettes can increase a person\'s risk of atherosclerosis, which is the buildup of plaque in the blood vessels. This buildup limits blood flow and can lead to dangerous blockages. The ill- effects of smoking cigarettes do not only affect people who smoke. Secondhand smoke can also have significant health effects. 2. **Alcohol Consumption:** can cause short and long-term effects on the cardiovascular system. Short-term effects include slower pulse rate, difficulty in breathing, and lower blood pressure. Long-term effects like persistent high blood pressure, cardiac muscle anemia, and strokes are experienced due to prolonged exposure to alcohol abuse. 3. **Over-eating:** it refers to eating more calories than your body uses for energy. People sometimes overeat for emotional or psychological reasons, such as boredom, anxiety, depression, or stress. It can lead to a host of health problems which include obesity, heart disease, high blood pressure, and high cholesterol. That is why it is important to get your food portions under control. 4. **Inactive lifestyle:** a lifestyle with a lot of sitting and lying down, with very little to no exercise. People are spending more and more time doing sedentary activities. An inactive lifestyle can affect our bodies. It burns fewer calories, and this makes more likely to gain weight. The metabolism may be affected, and your body may have trouble breaking down fats and sugars. The immune system will not work well, poor blood circulation, the body has more inflammation and develop a hormonal imbalance. **Health risks of an inactive lifestyle in the Respiratory System:** - **Asthma:** is the periodic construction of the bronchi and bronchioles that makes breathing difficult and triggers coughing, a whistling sound (wheezing) when you breathe out, and shortness of breath. - **Emphysema:** It causes the air sacs in the lungs (alveoli) are damaged. Over time, the inner walls of the air sacs weaken and rupture creating larger air spaces instead of many small ones. The gradual loss of gas exchange area focuses the heart to work harder to satisfy the body\'s needs for oxygen. The added strain can lead to heart failure. - **Tuberculosis (TB):** is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but they can also damage other parts of the body. TB spreads through the air when a person with TB of the lungs or throat coughs, sneezes, or talks. - **Lung Cancer:** can also occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes you\'ve smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer. - **Chronic Bronchitis:** is inflammation (swelling) and irritation of the bronchial tubes. These tubes are the airways that carry air to and from the air sacs in your lungs. The irritation of the tubes causes mucus to build up. **Health risks of an inactive lifestyle in the** **Circulatory System:** - **Obesity:** the abnormal or excessive fat accumulation that presents a health risk. - **High blood pressure (Hypertension):** increases the risk of serious health problems, including heart attack and stroke. - **Stroke:** is a brain attack, cutting off vital blood flow and oxygen to the brain. It happens when a blood vessel feeding the brain gets clogged or bursts. - **Depression:** is a mood or disorder that causes a persistent feeling of sadness and loss of interest. - **Anxiety Disorder:** frequently have intense, excessive, and persistent worry and fear about everyday situations. - **Atherosclerosis:** is a narrowing of the arteries caused by a buildup of plaque. Arteries are the blood vessels that carry oxygen and nutrients from your heart to the rest of your body. - **Coronary Artery Disease:** caused by plaque build-up in the wall of the arteries. - **Arteriosclerosis:** Arteriosclerosis is the narrowing of arteries due to plaque buildup on the artery walls. It happens when the endothelium (a thin membrane that lines the inside of the heart and blood vessels) becomes damaged, due to smoking, high blood pressure, and high levels of glucose, fat, and cholesterol in the blood. **Preventive Measures on how to Avoid Diseases of Respiratory and Circulatory Systems due to Lifestyle Practices:** 1. A good healthy diet Can prevent you from becoming a victim of circulatory problems. 2. Maintain a healthy weight Follow a healthy diet, and if you are overweight or obese, reduce your daily intake by 500 calories for weight loss. 3. Do not smoke If you want to stop smoking you can make small changes to your lifestyle that may help you to resist the tempt. 4. Regular Exercise a minimum of 30 minutes a day. It makes breathing quick, and the exchange of gases between the lungs and the blood becomes more efficient. 5. Maintain a healthy low-fat, low cholesterol diet with more fruits, vegetables, and whole grains. Avoid trans-fat and saturated fats which are often found in processed foods and fast food. **Lesson 2 Gene Location and Chromosomal Basis of Inheritance:** A diagram of a structure Description automatically generated - **Cell** - A cell is the smallest unit of an organism and cells are known as the building blocks of life. Most human cell types contain a nucleus. - **Nucleus** - The nucleus controls the cell, but it is also where genetic information is stored. The nucleus contains structures called chromosomes. Chromosomes are made of DNA. - **Chromosome**: - Each chromosome is made up of a single molecule of DNA. The cross shape we associate with chromosomes arises when the DNA copies itself, coils and condenses for cell division (mitosis). - Each human body cell contains 46 chromosome (23 pairs). The pairs carry the same types of genes. People with specific conditions and syndromes may have an extra chromosome. - The 23rd pair of chromosomes are known as the sex chromosomes. In females, the chromosome pair are identical and known as XX. In males, the chromosome pair are different and known as XY. - **DNA**: - You are what you are because of your DNA. Your height, the shape of your nose, your complexion, and other traits are controlled by your DNA. - DNA (deoxyribose nucleic acid) carries the genetic information of an organism. A section of DNA is known as a gene. Genes contain the code to produce a particular protein within a cell. - Deoxyribonucleic acid is often referred to as the code of life because it contains the information needed to form and control the physical makeup and chemical process of an organism. - In 1953, James Watson and Francis Crick discovered that DNA is a \"double helix.\" The shape of DNA is a double helix, which is like a twisted ladder. The sides of the ladder are made of alternating sugar and phosphate that serve as the backbones of the DNA. - The structure of DNA is made up of nucleotide molecules, which are considered the building blocks of DNA. Each nucleotide unit consists of three different molecules: the deoxyribose sugar, the phosphate group, and the nitrogenous bases. - The nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T). The paired nucleotides, which always occur as A -T or G -C, are linked by hydrogen bonds. This is called the complementary base pairing. - **Gene:** - Gene is the basic physical and functional unit of heredity. It controls the expression of physical characteristics or traits in an organism, such as how we look: the color of our eyes, how tall we are, the shape of our nose, etc. - It's made up of DNA segments (nucleotides) that are arranged in a particular sequence. Each gene has a particular location on the chromosome called locus (loci). - This sequence consists of three letter words that code for specific instructions to the cells, especially in the production of materials for the cell to use. There are two copies of genes because chromosomes came in pairs. Thousands of genes make up each chromosome. **Lesson 3 Non-Mendelian Patterns of Inheritance:** 1. **Incomplete Dominance:** - Incomplete dominance occurs when one allele for a specific trait is not completely dominant over the other allele. - The trait lies somewhere between the characteristics of both parents. - This results in the formation of the third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes. - In this trait, a completely dominant allele does not occur. - An example of incomplete dominance is the flower color in the four o\'clock plant. - When a pure red-flowered (RR) four o\'clock plant is being bred with a pure white-flowered (WW) plant, the resulting color of the flower is pink (RW). 2. **Sex-Linked Traits:** - Humans have 46 chromosomes or 23pairs of chromosomes in each cell except for the sperm and egg cells. Twenty-two pairs are the somatic chromosomes, and the 23rd pair consists of the sex chromosomes. - Human males have non-identical sex chromosomes (XY), while females have identical sex chromosomes (XX). - Hemophilia and color blindness are examples of X-linked traits. - Hemophilia is an inherited disease in which a person\'s blood does not clot easily which leads to persistent bleeding. - Color blindness happens when someone cannot distinguish certain colors like green, red, and blue. - The ability to discriminate between the colors red and green is controlled by a gene located in the X-chromosome. - The inability to distinguish between the two colors is due to the recessive allele of this gene. - Hypertrichosis Pinnae Auris is an example of a Y-linked trait. This is a rare genetic disorder in humans that causes hairy ears. Since only male carries the Y chromosome, then only males can have this disorder. A father who has the condition will pass it on to all his sons and the sons of the next generations. 3. **Multiple Alleles:** - These are traits that are controlled by more than two alleles. However, only two of the many alleles can be present in an individual. - The inheritance of the ABO blood group antigens in humans is an example of multiple allele traits. There are three alleles of the gene governing this instead of the usual two. Alleles IA, IB, and i. The ABO blood type is determined by the presence or absence of two antigens, A and B. Allele i do not code for an antigen. **Lesson 4 Biodiversity and Evolution:** - **Biodiversity:** - The Tubbataha Reef Marine Park has a diverse population of marine life. You can see numbers of different species of organisms as compared to a coconut plantation where you can only one species that dominates. - A population is a group or cluster of the same species of living things within a certain area. - Biodiversity on the other hand refers to the variety of life found in the area. For instance, in a jungle community, some populations, such as fungi, centipedes, and ferns can be very large in number. Other populations such as snakes, elephants, and giraffes have fewer members. - **Biodiversity and Evolution:** - Populations can be of the same size, but they may have different densities. - When we consider the number of individual species per unit area, we are referring to the population density.  - The differences in population density in a community is attributed to many factors. - Population sizes change when new members move into the ecosystem and decrease when members move out. - The birth and death rate also affects the population's size. - Anything that limits the size of a population like certain environmental conditions are called limiting factors. - These limiting factors keep and moderates a population size and help balance an ecosystem. - Limiting factors include the availability of food, water, living conditions, light, temperature, and soil nutrients. - With the limited resources and limiting factors, an ecosystem can only hold a certain amount of population of species. This is called carrying capacity. - If the population size increases above the carrying capacity, organisms may die because they cannot meet all their needs. - **Three Levels of Biological Diversity:** 1. **Genetic diversity --** This refers to the total sum of genetic information contained in the genes of organisms. 2. **Species diversity --** This refers to the measure of the number of different species in an area. 3. **Ecosystem diversity --** This refers to the measure of the different kinds of ecosystems in an area. - **Benefits from Biodiversity:** - Some see it as a source of income, forest materials are used in producing products that we use in our day-to-day life. This includes furniture, lumber for our shelter, and papers. - Some are used as raw materials for medicines, this includes medicinal plants. - Some see it as a source of happiness as natural parks give relaxation and peace of mind. - Most importantly it gives our necessities such as oxygen and food. - **Endangered Species:** - When a species population decreases and becomes so low that only a few remain, the species is considered endangered and is at risk of extinction. - In the Philippines, some terrestrial species like the tamaraw in Mindoro, mouse deer in Palawan, Philippine deer, Monkey-eating eagle, and aquatic species like the dugong found in Negros, Batangas, and Leyte are in danger of extinction. - In some instances, a species declines so fast that it becomes endangered and is said to be threatened. - In a study conducted by field biologists on population size and distribution of Philippine fauna, they reported that as of 1991, 44 species of mammals, 89 species of birds, and 8 species of reptiles are internationally recognized as threatened. - These include also the Philippine eagle or Monkey eating eagle in the list of Philippine endangered species. - **Extinction:** - Extinction is the total disappearance of a species when the last of its members die. - Species are threatened due to the changes to habitats. These changes are brought about by the increase in human population. - The impact of our growth and development is altering the natural system of the Earth and is pushing many other species to the brink of extinction. - **Factors that affect Extinction:** 1. **Deforestation:** - It is the rapid rate of which trees are cut down. - Major causes are Kaingin farming, illegal logging, conversion of forest lands to agricultural lands, housing projects, forest fires, and typhoons. Increase in population - As human population gets bigger, huge space is needed for shelter, for growing crops and farming, and for industries. - The growing number of populations comes the growing demand for all resources and services. - This includes conversion of forest lands into agricultural and residential areas. This disrupts the natural habitat of native species. 2. **Water Pollution:** - This occurs when too much of foreign materials get into the water system. One major problem in polluted rivers, lakes, and ponds is eutrophication. - It happens when the concentration of organic nutrients such as phosphorus, and nitrogen that comes from domestic garbage, farms lands, and industries are thrown in bodies of water. - The nutrients increase rapidly which cause algal bloom. - This algal bloom brings harm in the marine environment due to the harmful molecules it releases. - Algal blooms develop on the surface preventing light penetration and oxygen absorption necessary for underwater life. - Cultural eutrophication occurs when human water pollution speeds up the process by introducing sewage, detergents, and fertilizers in the water system. 3. **Fish Kill:** - A 'fish kill' usually happens when the algal bloom caused by eutrophication dies off, they sink to the bottom and the process of decomposition proceeds. - This process uses oxygen and as a result aquatic animals die due to lack of oxygen. - Bodies of water also get polluted with toxic wastes, untreated sewage, and fertilizer run-offs from farmlands which contributes to water pollution. - One class of dangerous chemicals present in polluted water is PCB (polychlorinated biphenyl). - PCBs are toxic wastes produced in the making of paints, inks, and electrical insulators. Water pollution 4. **Air pollution:** - According to the World Health Organization (WHO), is the contamination of the indoor and outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. - Pollutants can enter the air as gases, liquids, or solids. - Cars burn fuel and produce harmful gasses such as carbon dioxide, nitrogen oxides, and hydrocarbons. - Pollutants include particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. 5. **Destruction of Coastal Resources:** - Coral reefs and coastal mangrove forests serve as breeding grounds and nurseries of marine fishes. - The mangrove forests serve as natural barriers when high altitude waves hit the coastal areas. 6. **Climate Change:** - It is the rising in the average temperature of the Earth. - This occurs due to the different human activities that cause an enhanced greenhouse effect. - This change causes global warming and in return causes sudden and unpredictable weather disturbances such as colder winters and very dry summers. - In the tropical region, this affects the intensity of the typhoons as well as their occurrence. - It also carries different harmful effects such as sea level rising due to the melting of ice caps, ocean acidification, coral bleaching, and alike. 7. **Introduced Species:** - Also known as invasive species. This refers to the species that are brought by humans in a foreign land. - When a species is not a native to an area, it does not have any natural predator. Predators are important organisms in an ecosystem. They are responsible for the balance in the food web as well as the ecosystem. - When one species does not have a natural predator in the wild, they may reproduce exponentially and would damage the natural habitat of the native species in the area. Most often, these invasive species are introduced in an area as pets, as food source, as an initial Introduced species. - Most often, these invasive species are introduced in an area as pets, as food source, as an initial solution to a pest infestation, or by accident. - Notable invasive in the Philippines are cane toad "Bull frogs\'\' which were used as a pest control method in sugar cane plantations and is now present nationwide, Knife fish in Laguna Bay which was believed to be introduced in Laguna Bay by a flooding in 2009, Finlayson's Squirrel which were pets and have been seen in Metro Manila, Nueva Ecija, and Batangas. - In plants, one notable example is the water hyacinth which clogs the river and lakes in the country. - While it plays a beneficial role in removing heavy metals in polluted waters, it also has a bad effect as it covers the water surface limiting the sunlight and oxygen level in waterways. - **Sustainable Development:** - This means that a sustainable society should live under the carrying capacity of the environment and that the rate at which society uses renewable resources does not exceed the rate at which the resources are generated. - In simple manners, we can also help in the movement towards saving our biological diversity. - Choose lesser plastics. Plastics are not biodegradable. When going to the supermarket, opt to bring your own eco bag. - Walk when you can. Transportation contributes to carbon emission. More walking means lesser carbon emission. - Reduce, Reuse, Recycle. Practice the 3-R's. Instead of buying bottled water, bring your own tumbler, use cloth in wrapping your food instead of plastic. - Do not burn your garbage. Segregate your garbage. Turn your biodegradables into compost. And use less items that will end up in the garbage pile. **Lesson 5.1 Photosynthesis:** A green and yellow text Description automatically generated - Plants (Autotrophs) are known to be efficient producers of their own food. - Food production takes place in the leaves of plants. The leaves serve as a food factory. - A leaf is considered a chemical factory that releases oxygen and combines carbon dioxide and water to form sugar and starch. - Leaves provide living things with food as well as oxygen. - The leaves of the plants have green pigments called chlorophyll stored in the chloroplast. - The chloroplast is responsible for enabling photosynthesis to occur so that the plants can convert sunlight into chemical energy. - The chloroplasts can be found in the cells of the mesophyll in plant leaves. - There are usually 30-40 mesophyll cells. - The chloroplast has an inner and outer membrane with an empty intermediate space in between. - Inside the chloroplast are stacks of thylakoids, called grana (granum: singular), as well as stroma, the dense fluid inside of the chloroplast. - These thylakoids contain the chlorophyll that is necessary for the plant to go through photosynthesis. - The space that the chlorophyll fills is called thylakoid space. - One granum is connected to another through stroma lamella. - A chloroplast contains 40-60 grana. A granum may have two or three-hundred thylakoids.  - **The Stages of Photosynthesis:** - **Harnessing sunlight:** 1. **Light Capture:** Pigments like chlorophyll absorb light energy, propelling electrons in photosystems. 2. **ATP Generation:** The released electrons create a flow that drives ATP synthesis, storing chemical energy. 3. **NADPH Production:** Another stream of electrons generates NADPH, an energy and electron carrier molecule. 4. **Oxygen Release:** The water molecule splits, releasing oxygen crucial for the atmosphere and respiration. - **Transforming energy:** 1. **CO2 capture:** The enzyme RuBisCO fixes carbon dioxide (CO2) into organic compounds in the Calvin cycle. 2. **Sugar formation:** The resulting molecules convert into sugars, utilizing ATP and NADPH from the light-dependent phase. 3. **RuBisCO regeneration:** Molecules enabling CO2 capture regenerate, ensuring cycle continuity. 4. **Readying for new cycles:** The cycle persists, creating sugars and regenerating molecules for CO2 fixation in future iterations. A diagram of a plant Description automatically generated - **Dark Reaction:** - The dark reaction is also called the carbon fixation or Calvin- Benson Cycle, named after its discoverers, Melvin Calvin and Andrew Benson. - It takes place in the stroma of the chloroplast. - This stage can also occur even in the presence of light, although it does not have any use for light in the process. 1. Carbon dioxide enters the leaf through the stomata. It goes into the mesophyll layers and moves to the stroma of the chloroplast. 2. Here, carbon dioxide collides with 5-carbon compound called ribulose-1, 5 biphosphate (RUBP) to yield a 6-carbon containing sugar. The process is catalyzed by RUBP carbonxylase. 3. The 6-carbon compound is broken into two molecules of 3-carbon sugar, phosphoglycerate (PGA) (This requires two molecules of ATP). 4. The 2 molecules of PGA are converted into 2 molecules of phosphoglyceraldehyde (PGAL), a 3- carbon compound (PGAL is the first stable product of photosynthesis) (It needs 2 molecules of NADPH). 5. RUBP is regenerated from PGAL for the process to continue. A molecule of ATP is needed for the regeneration process. 6. The dark reactions complete the series of changes that light energy undergoes. 7. Through the dark reactions, chemical energy in ATP becomes stored in sugar  A close-up of a white background Description automatically generated **Lesson 5.2 Anatomy of a Leaf:** - A leaf is a flattened, lateral (meaning growing from the side) outgrowth from the stem of a vascular plant. In most cases, leaves are green and contain chlorophyll, which makes them the primary site of photosynthesis. - Beyond photosynthesis, leaves also play other roles in the plant\'s life, such as transpiration (releasing water vapor), gas exchange, and protection from sunlight and herbivores. - **Anatomy of a Leaf:** 1. **Cuticle:** A waxy layer covering the upper epidermis of the leaf, made of a substance called cutin. The cuticle acts as a waterproof barrier, reducing water loss from the leaf's surface. 2. **Upper Epidermis:** The single layer of cells covering the top surface of the leaf. Provides protection from water loss, UV radiation, and pathogens. It also secretes a waxy cuticle. 3. **Mesophyll:** The tissue between the upper and lower epidermis of the leaf, responsible for photosynthesis. Contains chloroplasts for capturing sunlight and carrying out photosynthesis. It's further divided into two types of cells. - **Palisade Cells --** Tightly packed cells that contain a high number of chloroplasts. They specialized in photosynthesis due to their abundance of chloroplasts for capturing sunlight. - **Spongy Mesophyll --** Irregularly shaped cells in the lower region of the mesophyll, containing air spaces between them. Allow for gas exchange within the leaf due to the air spaces. 4. **Chloroplasts:** These are specialized organelles within plant cells containing chlorophyll, the green pigment responsible for capturing sunlight during photosynthesis. Chloroplasts convert sunlight energy into chemical energy (glucose) through photosynthesis. 5. **Guard Cells:** A pair of specialized cells surrounding each stomata, responsible for opening and closing the pore. By changing their shape (inflating or deflating), guard cells control the size of the stomata opening, regulating gas exchange and water loss. 6. **Lower Epidermis:** The single layer of cells covering the underside of the leaf. Like the upper epidermis, it provides protection and contains more stomata for gas exchange. 7. **Stomata:** Microscopic pores on the leaf surface, allow for gas exchange (carbon dioxide intake and oxygen release). Controlled by guard cells, stomata open and close to regulate gas exchange and water loss 8. **Vascular Bundles:** A network of tubes within the leaf, transporting water, nutrients, and sugar throughout the plant. Xylem vessels transport water and minerals from the roots to the leaves. Phloem vessels transport sugar.  - **Chlorophyll:** - There are several types of chlorophyll. Examples are chlorophyll a and chlorophyll b. They are the best known and most abundant types of chlorophyll found in all autotrophic organisms except halobacteria. - Chlorophyll a is blue green and greatly absorbs red light wavelength. Chlorophyll a is the pigment directly involved in the transformation of light energy to chemical energy. - Chlorophyll b is yellow-green and absorbs blue light wavelength. Chlorophyll b is an accessory pigment, and like the other accessory pigments, it broadens the spectrum of light absorption in photosynthesis. - Chlorophyll b absorbs light of different wavelengths other than those absorbed by chlorophyll a. Chlorophyll b is yellow-green and absorbs blue light wavelength. - When a molecule of chlorophyll b absorbs light, the excited molecule transfers its energy to a molecule of chlorophyll a, which then transforms it into chemical energy - Some other pigments are the xantophylls which are yellow pigments and the carotenes which are the orange pigments (Both xantophyll and carotene absorb blue-violet light wavelengths). **Lesson 5.3 Factors Affecting the Rate of Photosynthesis:** - **Intensity of Light:** - Light provides the energy for photosynthesis. - When light is in excess, the rate of photosynthesis increases. - When much light energy is absorbed, more chlorophyll molecules are energized, causing them to capture more energy that can be used in the chemical reaction producing glucose or starch. - As light intensity is increased further, however, the rate of photosynthesis is eventually limited by some other factor. So, the rate plateaus. At very high light intensity, chlorophyll may be damaged, and the rate drops steeply. - Chlorophyll a is used in both photosystems. The wavelength of light is also important. PSI absorbs energy most efficiently at 700 nm and PSII at 680 nm. Light with a higher proportion of energy concentrated in these wavelengths will produce a higher rate of photosynthesis. - **Temperature:** - Most plants photosynthesize within the temperature range of 20 degrees Celsius to 40 degrees Celsius. - Temperature outside this range causes enzymes involved in photosynthesis to be nonfunctional. - Beyond 30°C, the rate of photosynthesis generally starts to decline. This happens because enzymes that facilitate photosynthesis, like RuBisCO, become less efficient at higher temperatures.  - **Availability of Raw Materials:** - Availability of carbon dioxide as well as water will also affect the photosynthetic rate. Shortage of water causes the stomata to close, thus carbon dioxide cannot enter the leaf. Therefore, no food can be produced. - An increase in the carbon dioxide concentration increases the rate at which carbon is incorporated into carbohydrate in the light-independent reaction, so the rate of photosynthesis generally increases until limited by another factor. - **Importance of Photosynthesis to Living Organisms:** - Living organisms rely on photosynthesis since it is the primary source of oxygen in the atmosphere. - The carbon cycle would not be possible without photosynthesis, oxygen-dependent life would perish, and plants would die. - Photosynthesis is the process by which green plants and trees produce food from sunlight, carbon dioxide, and water in the atmosphere: it is their principal source of energy. - The oxygen produced by photosynthesis is vital to human survival. - There would be little to no oxygen on the world without photosynthesis. **Lesson 6.1 Cellular Respiration:** - Cellular respiration is a metabolic pathway that breaks down glucose and produces ATP. A diagram of a cell cycle Description automatically generated - **Glycolysis** - Glycolysis is the process in which glucose is broken down to produce energy. - It produces two molecules of pyruvate, ATP, NADH and water. - The process takes place in the cytoplasm of a cell. - It occurs in both aerobic and anaerobic organisms.  - **Krebs Cycle** - Krebs cycle is a cyclic pathway of enzymatic reactions which oxidizes the compounds derived from glucose, fatty acids and amino acids in the matrix of mitochondria. - **Electron Transport Chain** - The electron transport chain is a series of four protein complexes that couple redox reactions, creating an electrochemical gradient that leads to the creation of ATP in a complete system named oxidative phosphorylation. - It occurs in mitochondria in both cellular respiration and photosynthesis.  - **Adenosine Triphosphate** - ATP is the source of energy for use and storage at the cellular level. - The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups. - **Aerobic Respiration** - A chemical process in which oxygen is used to make energy from carbohydrates (sugars). - Also called aerobic metabolism, cell respiration, and oxidative metabolism. A blue rectangle with black text and yellow circles Description automatically generated - **Anaerobic Respiration** - The oxidation of organic or inorganic substrates for ATP synthesis by oxidative phosphorylation using exogenously derived terminal (or alternate) electron acceptors other than oxygen. - Energy and ATP yields are always lower than those obtained using molecular oxygen.  A blue rectangles with black text Description automatically generated  - **Fermentation** - A process in which sugars are transformed into a new product through chemical reactions carried out by microorganisms. - **Pyruvate** - An organic molecule consisting of a 3-carbon atom backbone that plays a crucial role in both synthesis and breakdown pathways within organisms. - **NADH and FADH2** - FADH2 stands for Flavin adenine dinucleotide and NADH stands for nicotinamide adenine dinucleotide. - NADH and FADH2 play a role in several metabolic processes. - The Krebs cycle generates both NADH and FADH2. - By oxidative phosphorylation, NADH creates three ATP molecules, whereas FADH2 produces two. **Lesson 6.2 Parts of the Mitochondrion:** A diagram of a mitochondrion Description automatically generated - **Mitochondria** are called the **"powerhouses"** or **"energy factories"** of a cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy carrying molecule. ATP represents the short-term stored energy of the cell. - **Inner membrane:** encloses a fluid filled matrix. This membrane contains five complexes of integral proteins such as: - NADH dehydrogenase - Succinate dehydrogenase - Cytochrome c reductase (the Cytochrome b-c1complex) - Cytochrome c oxidase - ATP synthase - **Outer membrane:** encloses the entire structure that contains many complexes of integral membrane proteins that form openings. A variety of molecules and ions move in and out of the mitochondrion through the openings. - **Cristae**: a fold in the inner membrane of a mitochondrion and contains proteins and molecules used for making chemical energy for the cell. - **Matrix** is a gel-like material in the mitochondrion, or organelle that performs the process of aerobic respiration, that contains ribosomes resembling those of bacteria. It contains the mitochondrion\'s DNA, which also resembles that of bacteria.