Science Notes Consolidated (Chapter 12 - 14).docx

**[Chapter 12: Ecology (Interactions within Ecosystems)]** **How do our actions affect the environment?** Environment we live in provides limited resources Oceans: fish, seaweed Fossil fuels: energy for cars, electricity for air conditioning, mobile phones Our daily actions can impact the envir...

**[Chapter 12: Ecology (Interactions within Ecosystems)]** **How do our actions affect the environment?** Environment we live in provides limited resources Oceans: fish, seaweed Fossil fuels: energy for cars, electricity for air conditioning, mobile phones Our daily actions can impact the environment in both positive & negative manners **Negative Impact** **Positive Impact** --------------------------------------- ------------------------------------ Wasting Food Using public transport Using more electricity than necessary Reducing consumption Using more water than necessary Environmentally friendly practices Creating excessive waste Reforestation **Definitions:** What is conservation? Conservation: The protection and preservation of natural resources in the environment. What is Ecology? → Ecology is the study of the interactions of organisms with each other and with the environment. What is an ecosystem? → An ecosystem is made up of the interactions between a community and its physical environment. Define *mutualism*. → The relationship in which two or more organisms support or benefit one another. Importance of conservation: - \- Maintenance of a balanced ecosystem \- Maintenance of biodiversity \- Maintenance of a large gene pool \- Prevents extinction of animal and plant species \- Economic importance \- Rainforests are a source of raw materials for industries \- Food source \- Marine life are a major source of human food \- Preservation of natural scenery and wildlife **Examples:** Transportation uses fossil fuels which are burnt. Pollutant gases such as sulfur dioxide (acid rain) and carbon dioxide (greenhouse gas) \[GHG\] are released Human activities has increased the concentration of GHGs which trap heat within the earth atmosphere, contributing to climate change public transport move more people per vehicle, and release less air pollutants per unit kilometre for each person than when compared to a private car with fewer passengers; Reduced use of petrol or fossil fuel which reduce releases of carbon dioxide, a greenhouse gases and other pollutants All livestock require resources: land space, water, grain or grass. Cattle, when reared, release large amounts of methane, a GHG that traps heat in the atmosphere, contributing to climate change. Eating plant-based food can reduce the carbon footprint of individuals. **Environments influence the survival of organisms** Physical factors: - - - - - - - which are measured by instruments such as dataloggers and probes Examples: Why can only a few plants and animals survive in the hot desert and the north/south poles? Due to extreme temperatures and lack of water, life is not abundant in hot deserts. Due to the extreme cold, regions near the North and South poles have a lot of water in the form of ice. Only plants that have shallow root systems and mature quickly can survive long periods of darkness during winter months. **Adaptations in Organisms:** - - - - **Environment: Rainforest** **[Physical factors of its environment:]** - - - - - - **Mangrove:** **[Physical factors of its environment:]** - - - - - **Physical environment & population:** All organisms are adapted to live in their environment If there are changes to the habitat or physical conditions, the population will be affected, likely decreasing because organisms die So it is important to maintain the EQUILIBRIUM of an ecosystem! Organisms of the same kind living in the same environment form a population. Different populations of plants and animals living and interacting in a particular environment make up a community. The interactions between a community and its physical environment make up an ecosystem. **Types of Interrelationships in an Ecosystem:** [Predator-Prey relationship:] Predators hunt and kill their prey for food. What are some of the adaptations that allow predators to hunt successfully? → Sharp teeth, strong claws and high speed What are some of the adaptions that help the prey to avoid being caught by their predators? → Effective camouflage, defensive body parts like horns, small size and high speeds. [Mutualism:] Mutualism The relationship in which two or more organisms support or benefit one another. [Parasitism:] - - - - [Energy from food in plants:] - - - **Food chain:** - - - [Consumers:] Consumers are organisms that obtain organic nutrients, hence energy, from feeding on other organisms. [Types of consumers:] Herbivore: an animal which feeds on plants to obtain organic nutrients (all herbivores are primary consumers). Carnivore: an animal which feeds on other animals to obtain organic nutrients (all carnivores belong to the trophic level of secondary consumers or higher). Omnivore: an animal which feeds on both plants and animals to obtain organic nutrients. **Trophic Levels:** Trophic level: the feeding position a population of organisms occupies in a food chain **Decomposers:** - - - Examples: Bacteria, fungi, termites and earthworms are examples of decomposers. Why are they important? → Without decomposers, the nutrients found in dead organisms and their waste would not be returned to the environment. **Energy in an ecosystem:** - - - - - - - - [Why do food chains usually only have 4 or less links?] As there will not be enough energy to sustain the top consumer in longer chains. **[Chapter 13A: Electricity I]** **What is electricity?** - - - - +-----------------------------------+-----------------------------------+ | Closed Circuits | Open Circuits | +===================================+===================================+ | A closed circuit is one in which | Incomplete circuits are called | | all the components are joined | open circuits. | | together without any gap. | | | | Electric charges cannot flow in | | Electric charges can flow through | an open circuit | | a closed circuit. | | +-----------------------------------+-----------------------------------+ **Direction of an electric current:** - - **[Circuit components:]** 1\. Cell/ Battery - - 2\. Switch - -  3\. Bulb - - 4\. Resistors - -  **[Circuit symbols and diagrams:]**  **[Electric current: ]** - - - [Connecting the ammeter:] - - - **[Voltage:]** The voltage across a particular component in the circuit can also refer to the energy converted per unit charge. (e.g. A 1.5V cell means that the battery uses 1.5 J to drive 1 unit of charge around the circuit.) - - - -  **[Connecting the voltmeter]** - always connected in **parallel** across a cell or component in a circuit - red terminal (+) connected to (+) terminal of cell - black terminal (-) connected to (-) terminal of cell **[What happens when you connect multiple cells together?]** +-----------------------------------+-----------------------------------+ | Series | Parallel | +===================================+===================================+ | Total voltage across all the | Voltage across all the cells is | | cells = the **sum** of the | the **same** as the voltage | | voltages of the individual cells. | across a **single cell.** | | | | | **Total V = V~1~ + V~2~ + V~3~** | **Total V = V~1~ = V~2~ = V~3~** | +-----------------------------------+-----------------------------------+ **[Resistance]** - The opposition of a material to electric current passing through it is called electrical resistance. - Resistance results in a change of electrical energy into heat or other forms of energy. - Electric charges lose energy to the atoms and the atoms move faster upon gaining energy, causing the conductor to heat up. **Electrical conductors vs insulators:** - Electrical insulators have very high resistance. - They do not allow electric current to pass through them. - Good electrical conductors have much lower resistance than electrical insulators. - The SI unit of electrical resistance is the **ohm (Ω)**. **1) Fixed resistor** -- the resistance cannot be changed **2) Variable resistor (Rheostat)** The resistance of rheostat can be changed.  **To measure resistance directly:** A **multi-meter** or **ohmmeter** measures the **resistance** of a resistor. **[Total effective Resistance]** Resistors may be connected in series or parallel circuits. **In series** - - - **In Parallel**: - - - - **[Relationship between V, I and R]** Ohm's Law:  **[Effects and applications of an electric current]** An **electric current** can produce - - - - - - - - - - - **Color of the three wires:** Live wire (brown) Earth wire (yellow-green) Neutral wire (blue) Under normal operating conditions, current flows through the live and neutral wires but not the earth wire. Potential of the wires: 1. 2. 3. **[Safety Features]** - - - - - - - - - - - **[Electric Power and Energy]** - - - - The **amount** **of** **electrical energy consumption** can be calculated by the formula: **Electrical energy (kWh) = Power** **(kW)** **×** **Time (h)** - **[Calculating electrical energy ]** - - **[Cost of electrical energy]** To find the total cost of energy: Total cost = Electrical energy (kWh) **×** unit cost of energy **[Chapter 14: Digestion in Humans]** **[What are nutrients?]** **Nutrients are chemical substances in food that provide energy and materials needed by the body.** [Types of nutrients:] Carbohydrates, proteins, fats - - The human digestive system consists of the **alimentary canal** and the **organs** associated with it.  1. Ingestion: [intake] of [food] into the [alimentary canal] through the [mouth] Digestion of carbohydrates (starch) occurs to form partially digested carbohydrates. → Digestion of carbohydrates starts in the mouth, broken down by the enzyme carbohydrase. 2. a narrow, muscular tube that extends to the stomach. 3. - which is a **muscular** bag. - secreted by the **gastric glands**. - - 4. - - - - 5. - - **[Peristalsis]** - - - **Physical** digestion **Chemical** digestion --------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------- Mechanical break up of large pieces of food into smaller pieces Enzymes break down large, insoluble nutrient molecules to soluble, simple molecules To increase surface area to volume ratio for enzymes to act on more efficiently/at a faster rate. that are small enough to diffuse across partially permeable cell membranes to be absorbed into body cells **Why does food need to be digested?** **What are the final products of digestion?**  **What happens to the digested food after it is being absorbed into the bloodstream?** - - - **[How is food digested in the different parts of the alimentary canal?]** 1. **[Physical digestion:]** The **[chewing]** action of teeth **crush large pieces of food into smaller pieces** (physical digestion) **[Chemical digestion:Saliva]** in the mouth contains **carbohydrases**. **[Partial]** digestion of starch, a type of carbohydrate, begins in the mouth.\*\* 2. **[Physical digestion]** - When the food enters the stomach, it stimulates the release of **[gastric juice]** by the gastric glands. - - - - **Proteins are digested in the stomach.** **[Chemical digestion]** - protease breaks down large protein molecules into [smaller protein chains (**polypeptides**)]. 3. **Physical digestion:** ~~\ ~~break up of fat by bile **Chemical digestion:** small intestine is the main site for chemical digestion due to the numerous enzymes released. Fats are first digested here due to the presence of lipases in the digestive juices. Carbohydrates, proteins and fats are fully digested here **Absorption in the small intestine**. - - - **Absorption in the large intestine**. - **What happens to the undigested and unabsorbed matter?** - - - **Diabetes:** **What is Diabetes?** - - - - **[What are some issues that affect the human digestive system?]** 1. What is constipation? - - Prevention of constipation: - - 2. 3. What is food poisoning? - - - Preventing food poisoning: - - - - - - -