Life Processes: Maintaining Life

• Living beings can be identified by actions like a dog running, cow chewing, or person shouting
• Breathing, growing, and moving are common characteristics of life
• Molecular movement is essential for life, contributing to the debate on whether viruses are alive when not infecting a cell.
• Living organisms are well-organized structures that need to maintain themselves
• Maintenance requires repair and maintenance, which needs molecular movement

Life Processes

• Life processes are maintenance functions
• Life processes happen even when organisms are not actively doing anything like sleeping
• Energy from outside the body is needed to prevent damage and break-down
• All organisms need nutrition, which is defined as how energy is transferred to an organism
• Carbon sources from food are required since life relies on carbon-based molecules
• Organisms use varied nutritional processes depending on carbon sources
• Energy sources undergo breakdown or buildup in the body by use of chemical reactions, before being converted to a uniform energy source
• Some organisms use oxygen to break down molecules, through respiration
• Single-celled organisms don't require specific organs for food intake, gas exchange, or waste removal
• Multicellular organisms need the previous due to cells may not directly contact the environment so simple diffusion is not enough.
• Specialized tissues are used for the function of food and oxygen uptake
• A transportation system, is required to deliver food and oxygen.
• Harmful or useless by-products are created during energy generation which are removed through excretion
• Organs for excretion are specialized in multicellular organisms

Nutrition

• Energy is required to maintain order in our bodies, even when resting
• Food provides energy and the materials needed for growth and synthesis

Food Acquisition

• Organisms can use simple inorganic materials like carbon dioxide and water
• Autotrophs, for example bacteria and plants, use simple food production
• Some organisms break down complex compounds and use enzymes in order to grow

Autotrophic Nutrition

• Requirements of carbon and energy which are met through photosynthesis
• Autotrophs take in substances and transform them into stored energy
• The energy comes from carbon dioxide and water converted to carbohydrates, by using sunlight and chlorophyll
• Plants store unused carbohydrates as starch for future use
• In animals, the energy is derived from food and stored as glycogen

Photosynthesis

• Light energy is absorbed by chlorophyll
• Water molecules split into hydrogen and oxygen via light energy being converted into chemical energy
• Carbon dioxide is reduced to carbohydrates

Cross-Section of a Leaf

• Some cells viewed under a microscope contain green dots
• Chloroplasts are organelles that contain chlorophyll and are found in plant cells

Stomata

• Stomata are small pores on the surface of leaves and are where the plant obtains carbon dioxide
• Gas exchange happens through these pores
• Water can be lost through stomata
• Stomata open and close based on the need for photosynthesis
• Guard cells control the opening and closing of the stomata

Raw Materials for Autotrophs

• Terrestrial plants get water from soil through the roots
• They take up minerals like nitrogen, phosphorus, iron, and magnesium
• Nitrogen is needed for synthesizing proteins and other compounds and which is taken up as inorganic nitrates or nitrites, or organic compounds from bacteria

Heterotrophic Nutrition

• An organism's environment and how it obtains food impacts its nutrition
• Strategies for obtaining and using food vary
• Some organisms break down food externally and absorb it
• Fungi such as bread molds, yeast, and mushrooms are examples
• Others ingest and break down whole materials internally which depends on body design and function
• Cuscuta, ticks, lice, leeches, and tapeworms derive nutrition without killing other organisms

How Organisms Obtain Nutrients

• Digestive systems differ organisms
• In single-celled organisms food is taken in through surface
• In complex organisms, there is specialization
• Amoeba use extensions of the cell surface to engulf food particles in vacuoles
• Complex particle broken down into simpler once and diffuse in cytoplasm
• Undigested material removed, while Paramoecium takes in food at a specific spot using cilia movement

Nutrition in Human Beings

• The alimentary canal, extending from mouth to anus, has regions that perform different functions

Activity 5.3 Action of Saliva on Starch?

• Process food by grinding with teeth
• Saliva is secreted which smooths the passage when the canal lining is soft
• Enzymes break down the complex nature of ingested food to smaller molecules
• Salivary amylase, which breaks down complex molecules to simple sugar in saliva
• The food is then mixed and moved by tongue
• The lining of the canal must have muscles that contract rythmically which pushes the food to be processed
• Regulated movements occur along the gut

Human Alimentary Canal

• Food goes down mouth to stomach through oesophagus
• Muscular walls of stomach help digestion by churning food + digestive juices
• Gastric glands release hydrochloric acid, mucus, and pepsin
• Hydrochloric acid creates an acidic medium facilitating pepsin and the mucus
• Pepsin is a protein digesting enzyme

The Small Intestine

• Food exits the stomach, which is regulated by a sphincter muscle that releases it in small amounts into the small intestine.
• It is the site of carbohydrates, fats, and proteins complete digestion
• It receives secretions from liver and the pancreas
• Food from stomach must be alkaline
• Bile juice from the liver makes the food alkaline which acts on fats
• Breaks them down into smaller globules increasing efficiency
• Pancreas secretes pancreatic juice like trypsin for proteins and lipase for fats
• Small intestine walls have juice and enzymes
• They convert amino acids, glucose and glycerol

More on Villi

• Inner small intestine lining is absorbed by the walls
• They are richly supplied to blood vessels that bring absorbed food in energy to the whole body

Large Intestine

• Indigestible food is sent to the large intestine where water is absorbed from it through the walls

Dental Caries

• Dental caries causes tooth decay and begins when bacteria softens enamel from sugars
• Bacterial cells form dental plaque
• Saliva cannot reach tooth to neutralize acid because of plaque
• Brushing after eating removes plaque
• Untreated microorganisms can lead to pulp, inflammation and infection

Respiration

• Diverse organisms use different ways to use food for energy
• Some use oxygen to fully breakdown the glucose into carbon dioxide and water
• Glycolysis is the first step and breaks down glucose into pyruvate in cytoplasm
• Yeast converts glucose to ethanol and carbon dioxide
• Anaerobic respiration means the process occurs in absence of oxygen in cytoplasm
• Aerobic respiration's pyruvate breakdown happens in the mitochondria by using oxygen
• Lactic acid production occurs in muscle cells from energy generation resulting in cramps

Energy Release

• ATP (adenosine triphosphate) molecule transfers energy inside the cell
• ATP which is used in the body to fuel other activities, gives rise to a fixed amount of energy

Air intake

• O2 intake in aerobic respiration happens via gas exchange through the stomata, ensuring that all cells are in contact with air
• CO2 and O2 exchange happens by diffusion
• Terrestrial and aquatic animals can take in oxygen
• Aquatics breathe in the oxygen that is already in their water
• Land animals breathe the O2 of air in the atmosphere
• Air intake through nostrils is filtered by fine hairs and mucus
• Air flows though throat to lungs via cartilage ring
• Lungs have passage divided into balloon-like structures called alveoli

Functioning

• Alveoli enable the exchange of gases
• Walls of alveoli form a network of blood vessels
• Flattening of diaphragm occurs when air is sucked into ribs which increase chest cavity
• Respiratory pigments enable transportation of O2 as diffusion pressure can't take care of oxygen delivery
• Hemoglobin used in humans to carry and release deficient oxygen
• Carbon dioxide is more water soluble

Advantage Over Aquatic Organism

• Aquatic organisms breathe the oxygen that is already in their water

Advantage Over Terrestrial Organism

• Land animals breathe the O2 of air in the atmosphere

What are the different ways in which glucose is oxidised to provide energy in various organisms?

• Yeast breaks down glucose into ethanol carbon dioxide
• Lactic acid production occurs in muscle cells

Transportation

• Blood transports food, oxygen, and waste materials
• It is a connective tissue
• Plasma is a fluid which carry the blood
• RBCs carry O2

Double Circulation

• Heart separates the circulation of oxygenated and deoxygenated blood.
• Oxygenated blood goes to thin-walled upper chamber of heart (left atrium)
• Left atrium then transfers blood to muscular left ventricle
• Deoxygenated blood from upper body reaches right atrium as it relaxes
• Right atrium contracts which sends the blood to the right ventricle
• Right ventricle then pumps the blood to the lungs for oxygenation
• Ventricles have thick muscular walls than atria
• Fish only pump blood through the heart once, which goes into gills, passes on to rest of body, only one cycle
• Birds use energy to maintain body temperature. Fish use environmental temperature

Blood Pressure

• Blood pressure is force of blood against the wall of a vessel, greater in the arteries
• Systolic pressure in artery is during arterial systolic pressure
• Diastolic pressure is artery during arterial diastole
• Pressure is read with instrument called sphygmomanometer
• High blood pressure happens when arterioles are constricted
• Causes increased resistance

Vessels

• Arteries carries blood away from heart to organs and have thick walls
• Veins collect blood from organs to heart
• Veins have valves
• Materials exchange around blood which is one celled capillaries
• Blood platelets plug system if tube has leak to lower bleeding

Lymph

• Lymph or tissue fluid transports fluid
• Form tissue fluid
• Lymph drains capillaries
• Carries fat from intestine

Plants

Transportation

• Plants transport minerals and energy
• Xylem transports water and minerals found from soil
• Phloem transports products

Transport of Water

• Xylem and tracheids connect
• Water enters with ion uptake creating steady water
• Transpiration helps absorption of water from roots
• Pull moves water in xylem

Excretion

• Metabolic wastes are removed through the biological process where the removal of harmful waste and material called excretion
• Unicellular animals perform excretion by moving their body's surface into surrounding water
• Multicellular animals take water surrounding to help
• Nitrogenous wastes excreted by kidneys
• Kidneys have tube called the Bowman's capsule.

Artificial Kidney

• Failure leads to toxin
• Use device to waste via dialysis

Plants

• O2 waste product, excess water by transpiration
• Get rid of material thru dead leaves
• Plant toxins