Exam Notes on Interactions between Organisms, Metabolism, Systems, and Cells

Interactions Between Organisms

• Environment: Air, water, and organisms around a living thing.
• Habitat: Place where an organism lives.
• Population: Group of the same species in an area.
• Community: All living organisms in a habitat.
• Ecosystem: Community interacting with non-living things.

Food Chains

• Energy moves from one organism to another.
• Start with a producer (plant).
• Trophic levels: Steps in the chain (producer → herbivore → carnivore).
• Animals:
  • Herbivores: Eat plants.
  • Carnivores: Eat animals.
  • Omnivores: Eat both.
  • Decomposers: Break down dead things (fungi, bacteria).
• Autotrophs (Producers):
  • Make their own food using sunlight.
  • Example: Plants, algae.
• Heterotrophs (Consumers):
  • Cannot make food; eat plants or animals.
  • Example: Humans, lions, cows.

Food Webs

• Network of connected food chains.
• Show organisms eat/are eaten by multiple things.
• Energy decreases at each level.
• Human impact: Pollution, hunting, deforestation can break food webs.
• Nutrient cycle: Nutrients recycled by decomposers.

Trophic Levels

• Level 1: Producers (grass, algae, trees).
• Level 2: Primary Consumers (caterpillars, rabbits).
• Level 3: Secondary Consumers (birds, frogs).
• Level 4: Tertiary Consumers (snakes, foxes).
• Level 5: Apex Predators (eagles, sharks, lions).

Energy Flow Through Food Webs

• Energy starts from the Sun.
• Plants use sunlight (producers).
• Animals eat plants/animals (consumers).
• Energy lost as heat at each step.
• Example: Sun → Grass → Rabbit → Fox

Human Impact on Food Webs

• Change/harm food webs through deforestation, pollution, overfishing, introducing new species, and climate change.

Nutrient Cycle

• Plants take nutrients from the soil.
• Animals eat plants.
• Decomposers return nutrients to the soil.

Greenhouse Effect

• Sun sends energy as short-wave radiation.
• Earth absorbs energy, sends back as long-wave radiation (heat).
• Greenhouse gases trap heat.

Main Greenhouse Gases

1. Water vapour
2. Carbon dioxide (CO₂)
3. Methane (CH₄)
4. Nitrous oxides (NOₓ)

Factors Affecting Greenhouse Gas Impact

1. How well it absorbs heat
2. Concentration in the air

Impact of Greenhouse Gases

• Carbon Dioxide: Long-term impact due to slow removal and long life in the atmosphere.

Nutrients in Human Diet

• Macronutrients: Proteins, lipids, carbohydrates.
• Micronutrients: Vitamins, minerals, water, fibers.

Minerals and Vitamins

• Minerals: Natural solids essential for growth.
  • Calcium: Bones and teeth (milk, cheese, fish).
  • Deficiency: Rickets.
  • Iron: Hemoglobin (liver, red meat, dark green vegetables).
  • Deficiency: Anemia.
• Vitamins: Natural substances needed in small amounts.
  • Vitamin A: Eyes (fish liver oil, carrots).
  • Deficiency: Poor night vision.
  • Vitamin C: Gums (citrus fruits, green vegetables, black currants).
  • Deficiency: Scurvy.
  • Vitamin D: Calcium absorption (fish liver oil, butter, sunlight).
  • Deficiency: Rickets.

Deficiencies

• Rickets: Softening of bones (vitamin D, magnesium, phosphorus, or calcium deficiency).
• Anemia: Reduced red blood cells; less oxygen.
• Scurvy: Swollen gums, pain, shortness of breath, blurred vision.

Carbohydrates

• Energy-giving food (rice, potato, wheat, sugar).
  • Simple (monomer): Glucose, fructose, galactose.
  • Complex (polymer): Starch, fibers, glycogen.

Fats

• Lipids: Energy storage, insoluble in water.
• Lipids made of 3 fatty acids and 1 glycerol.

Proteins

• Made of amino acids.
• 20 different amino acids.

Digestion

• Epiglottis: Switch between esophagus and trachea.
• Mouth:
  • Teeth break down food.
  • Tongue mixes food with saliva forming a bolus.
  • Salivary glands produce:
  • Water, Mucus, Amylase
• Esophagus: Tube from mouth to stomach (peristalsis).
• Stomach:
  • Mechanical and chemical digestion.
  • Muscle contractions mix bolus with gastric juice to form chyme.
• Gastric juice:
  • Mucus: lubricates food.
  • Pepsin: digests proteins.
  • Hydrochloric acid: kills bacteria, breaks down bolus, provides optimum condition for pepsin.
• Small intestine:
  • Digested food absorbed into blood.
  • Duodenum: chemical digestion (pancreatic juice, bile).
  • Ileum: food absorption.
• Pancreatic juice enzymes:
  • Amylase, trypsin, lipase, sodium hydrogen carbonate.
• Bile:
  • Emulsifies fats.
• Villi:
  • Maltase, sucrase, lactase, peptidase, lipase.
• Large intestine:
  • Absorbs water and salt.
  • Excretes waste.
• Assimilation: Nutrients enter cells via hepatic portal vein.
• Liver:
  • Glucose stored as glycogen; amino acids changed to urea.

Gas Exchange

• Oxygen in, carbon dioxide out.
• Alveoli in lungs facilitate gas exchange.

Aerobic vs. Anaerobic Respiration

• Aerobic: With oxygen, in mitochondria, complete glucose breakdown, more energy, end products are carbon dioxide and water.
  • Equation: $C<em>6H</em>{12}O<em>6 + 6O</em>2 \longrightarrow 6CO<em>2 + 6H</em>2O + energy$
• Anaerobic: Without oxygen, in cytoplasm, incomplete glucose breakdown, less energy. Animals produce lactic acid (no CO2); plants produce ethanol and CO2.
  • Animals Equation: $C<em>6H</em>{12}O<em>6 \longrightarrow 2C</em>3H<em>6O</em>3 + energy$
  • Plants Equation: $C<em>6H</em>{12}O<em>6 \longrightarrow 2C</em>2H<em>5OH + 2CO</em>2 + energy$

Breathing Rate

• Breathing rate increases during exercise

Factors Affecting Human Health: Smoking

• Smoking damages lungs (tar, nicotine, carbon monoxide).
• Increases risk of lung cancer, heart disease, breathing problems.

Diseases Caused by Smoking

• Lung diseases (cancer, bronchitis, emphysema).
• Heart and blood problems (heart disease, stroke, high blood pressure).
• Weakened immune system, cancer, poor healing, harm to unborn babies.

Living Systems Characteristics

• Reproduce, Move, Expel Waste, React to Stimuli.

Photosynthesis

• Word: Carbon dioxide + Water → Glucose + Oxygen
• Chemical: $6CO<em>2 + 6H</em>2O \longrightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$
• Process by which plants produce carbohydrates from raw materials using energy from the sun.

Photosynthesis process

1. Light splits water, releasing oxygen and hydrogen ions
2. Carbon dioxide combines with hydrogen to make glucose.

Chlorophyll

• Green pigment in chloroplasts that absorbs sunlight.

Leaf Model Key Parts

• Epidermis. (Upper/Lower)
• Palisade mesophyll.
• Spongy mesophyll.
• Stomata.
• Guard Cells.
• Vascular Bundle

Plant Transport

• Xylem: Water and minerals from roots to leaves(unidirectional).
  • Transpiration: Water evaporates pulling more water up.
• Phloem: Food (sugars) up or down.
  • Translocation: Phloem process.

Xylem Functions

• Carries water and minerals from the roots to the rest of the plant
• Water flows in one direction — only upwards
• Also helps support the plant like a skeleton
• Made of long, hollow dead cells joined together to form tubes

Transpiration Stream

• Water moves from the roots up to the leaves through tubes called xylem
• This is called the transpiration stream
• Water moves upward, even against gravity

Key Definitions for Water Movement

• Cohesion: Water sticks to other water
• Adhesion: Water also sticks to the sides of the xylem

Pholem Functions

• Source to sink - Uses translocation

The Breathing System - Key Parts

• Ribs, Rib muscles, Right bronchus, Diaphragm, Trachea, Bronchiole, Alveoli

Alveoli Functions

• Thin walls, large surface area, moist surface, good blood supply, close to capillaries

Breathing Steps

1. Inhaling (breathing in):
2. Gas exchange in the lungs:
3. Exhaling (breathing out):

Cell Structure Components

Organelles in animal cells:

• Cell membrane
• Cytoplasm
• Nucleus
• Mitochondria
• Endoplasmic reticulum

Organelles in plant cells:

Plants contain all the organelles from animal cells in addition to these:

• Cell wall
• Chloroplasts
• Large vacuole

Specialized Cells

• Ciliated cell: Move mucus (cilia).
• Red blood cell: Transport oxygen (hemoglobin).

Muscle Movement

• Skeletal muscle is made of long cells called muscle fibers.
• Muscles are connected to bones by strong cords called tendons.
• Sarcomeres are the parts that actually contract (shorten).

Key Organs

• Brain, Heart, Lungs, Stomach, Liver, Small intestine, Large intestine, Kidneys, Bladder, Skin

Cell Division

1. Purpose:

• Mitosis
• Meiosis

1. Divisions:

• Mitosis: 1 division.
• Meiosis: 2 divisions.

1. Chromosomes:

• Mitosis
  • Meiosis

1. Stages:

• Mitosis
• Meiosis

1. Genetic Difference:

• Mitosis
• Meiosis

1. Function:

• Mitosis
• Meiosis

1. Cell Types:

• Mitosis
• Meiosis

Mitosis and Cell Cycle

• Interphase (G1, S, G2): Cell growth, DNA replication, organelle duplication.
• M phase: Mitosis, Cytokinesis
• Mitosis Stages: Prophase, Metaphase, Anaphase, Telophase.
• Cytokinesis: Cytoplasm splits; two identical cells are formed.

Sexual Reproduction

Female:

• Ovaries, Oviducts, Uterus, Cervix, Vagina.

Male:

• Testes, Scrotum, Sperm ducts, Urethra, Prostate gland.

Egg Production

• Females born with ~1 million eggs; ~300,000 by puberty.
• One egg released each month (ovulation).

Sperm Production

• Made in testes; need cooler temperatures.

Fertilization

• Implantation
• Sperm and egg nuclei join forming a zygote.
• Zygote moves to the uterus and is implanted

Key Structure in Developing Embryo

Placenta and Amnion

• Placenta: Forms for nutrient exchange.
• Amnion: Amniotic sac protects fetus.

Embryo Development

• Key weeks of development(6,8,10,11)

Labour Steps

• Contractions, cervix dilates, amniotic sac breaks, baby is born.

Puberty

• Sperm production starts in boys.
• Ovulation starts in girls.
• Secondary sexual characteristics develop.

The Menstrual Cycle

• Cycle lasts ~28 days.
• Day 14: Ovulation.
• 5-7 Days: Menstruation.

Key Hormones

1. FSH
2. LH
3. Progesterone
4. Estrogen

Sexual Reproduction differences

MALE AT BIRTH

• Testes have descended into scrotal sac but they do not make sperms yet

FEMALE AT BIRTH

• Ovaries containing immature eggs present in abdomen but they do not produce eggs yet

Birth control Types

• Natural, chemical, mechanical, surgical. (Give example for each)

What could cause the need for fertility Treatments

• Low sperm count or quality.

Three Main Types of Blood Vessels:

• Arteries: Away from the heart.
• Capillaries: Connect arteries and veins (exchange).
• Veins: Back to the heart.

Key Blood Vessels in the Heart

• Aorta
• Pulmonary Artery
• Vena Cava
• Pulmonary Veins

Blood Circulation

• Systemic: L Ventricle -> Body -
  R Heart.
• Pulmonary: R Ventricle -> Lungs -> L Heart.

The Heart - Key Facts

• ~300g, size of fist, in chest, pericardium, 4 chambers(atria, ventricles), septum prevents mixing of blood.

Coronary Heart Disease

• Plaque builds up in coronary arteries = less blood flow to heart muscle.
• Can lead to clots -> heart attack.

The Heart - Valve Function

• Valves in the heart help ensure blood flows in the right direction and prevent it from flowing backward. They also maintain the correct pressure in the heart chambers.

The Nervous System

• Central Nervous System (CNS) = Brain and Spinal Cord
• Peripheral Nervous System (PNS): Nerves.

Nervous System Controls - Key Functions

• Reflexes