Ecology: Energy Flow and Food Webs

Organisms and Their Environment

Energy Flow

• The sun serves as the main energy source for biological systems.
• Energy passes through living things, starting as light energy from the sun, then as chemical energy within organisms, before eventually being released into the environment.

Food Chains and Food Webs

• A food chain illustrates how energy is passed from one organism to the next, commencing with a producer.
• Constructing and interpreting simple food chains is essential to understanding energy transfer.
• A food web comprises multiple interconnected food chains and their interpretations.
• Producers are organisms that produce their own organic nutrients, primarily through photosynthesis, using sunlight.
• Consumers get energy by consuming other organisms.
• Consumers are classified as primary, secondary, or tertiary based on their position in the food chain.
• Herbivores are animals deriving energy from plants.
• Carnivores are animals deriving energy by consuming other animals.
• Decomposers obtain energy from dead or waste organic matter.
• Food chains and webs can show the effects of human actions, such as overharvesting or introducing foreign species, on a habitat.

Carbon Cycle

• The carbon cycle includes photosynthesis, respiration, feeding, decomposition, formation of fossil fuels, and combustion

Human Influences on Ecosystems

Habitat Destruction

• An ecosystem includes the community of organisms and their environment interacting together.
• Biodiversity refers to the number of different species inhabiting a specific area.
• Habitat destruction arises from increased land use for, housing, agriculture, and livestock.
• Habitat destruction also occurs due to extraction of natural resources and freshwater/marine pollution.
• Deforestation leads to reduced biodiversity, extinction, soil loss, flooding, and increased atmospheric carbon dioxide.

Conservation

• Organisms are endangered or extinct because of climate change, habitat destruction, hunting, overharvesting, pollution, and introduced species.
• Endangered species can be conserved through monitoring, habitat protection, education, captive breeding programs, and seed banks.

Gas Exchange in Humans

Gas exchange in humans

• Key components of the breathing system include the lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli, and associated capillaries.
• Physical activity impacts the rate and depth of breathing.
• Gas exchange surfaces in humans have a large surface area, thin surface, good blood supply, and good ventilation with air.

Respiration

Respiration

• Energy in living organisms is used for muscle contraction, protein synthesis, cell division, growth, and maintaining body temperature.
• Aerobic respiration involves chemical reactions where cells use oxygen to break down nutrient molecules and release energy.
• The word equation for aerobic respiration is: glucose + oxygen → carbon dioxide + water.
• The balanced symbol equation for aerobic respiration is: C6H12O6 + 6O2 → 6CO2 + 6H2O.

Diseases and Immunity

Disease and Immunity

• A pathogen is a disease-causing organism.
• A transmissible disease can be passed from one host to another.
• Pathogens transmit through direct contact (blood, body fluids) or indirectly (contaminated surfaces, food, animals, air).
• The body's defenses against pathogens include: skin, hairs in the nose, mucus, stomach acid, and white blood cells.
• Viruses have a protein coat and genetic material.
• Controlling disease spread involves clean water, hygienic food preparation, personal hygiene, waste disposal, and sewage treatment.
• Active immunity is a defense against pathogens achieved through antibody production in the body.
• Active immunity is acquired after infection or vaccination.

Drugs

Drugs

• A drug is any substance modifying or affecting chemical reactions in the body.
• Antibiotics treat bacterial infections.
• Some bacteria are resistant to antibiotics, reducing their effectiveness.
• Antibiotics only kill bacteria and do not affect viruses.
• Limiting antibiotic use prevents the development of resistant bacteria like MRSA.

Reproduction

Sexual Reproduction in Plants

• A insect-pollinated flower consists of: sepals, petals, stamens, filaments, anthers, carpels, style, stigma, ovary, and ovules.
• Pollination transfers the pollen grains from an anther to a stigma.
• Fertilization occurs when a pollen nucleus combines with a nucleus in an ovule.
• Seed germination needs water, oxygen, and a suitable temperature.
• Wind-pollinated flowers contain anthers and stigmas.

Sexual Reproduction in Humans

• The male reproductive system includes: testes, scrotum, sperm ducts, prostate gland, urethra, and penis.
• The female reproductive system includes: ovaries, oviducts, uterus, cervix, and vagina.
• Fertilization is the fusion of nuclei from a male gamete (sperm) and a female gamete (egg cell).
• The menstrual cycle includes changes in the ovaries and the lining of the uterus.