Life processes are the essential maintenance functions that keep living organisms alive and functioning. These processes continue even when organisms are resting or sleeping.

These maintenance processes require energy, which comes from outside the body through food. The process of transferring energy from food into the body is called nutrition.

Nutrition is the process by which organisms obtain and utilize food for growth, repair, and energy. Since life on Earth depends on carbon-based molecules, most food sources are also carbon-based.

Food sources need to be broken down into simpler molecules that can be used for:

• Energy production
• Cellular maintenance
• Growth and repair

Respiration is the process of acquiring oxygen from the environment and using it to break down food sources for cellular energy needs.

In single-celled organisms, respiration occurs through simple diffusion across the cell membrane. But in multicellular organisms, specialized respiratory systems are needed.

In multicellular organisms, simple diffusion is insufficient to meet the needs of all cells. This creates the need for a transportation system.

Specialized tissues and organs work together to ensure all body parts receive necessary materials.

Excretion is the process of removing harmful waste by-products created during energy-generating chemical reactions.

In complex organisms, specialized excretory tissues work with the transportation system to remove waste from cells.

Plants are nature’s chefs! They make their *own* food through **autotrophic nutrition** using sunlight, air, and water.

Plants cook food in 3 steps:

1. Sun Grab! → Chlorophyll absorbs light.
2. Water Split! → Light breaks water into Hydrogen + Oxygen.
3. Food Cook! → Hydrogen + CO₂ = **Carbohydrates**.

• Chloroplasts → Food factories
• Stomata → CO₂ in / Oxygen out
• Guard Cells → Close stomata on hot days to save water

Roots grab from soil:

• Water → For photosynthesis
• **Nitrogen** → To make proteins (like eggs for you!)
• Phosphorus/Iron → Plant “vitamins”

Organisms that **can’t cook their own food** are heterotrophs! They explore, hunt, or steal meals. Examples: You, lions, mushrooms, and even pesky parasites!

Fungi (mushrooms, yeast) are nature’s recyclers! They spit **digestive juices** on dead plants/food -> turn it into soup -> absorb nutrients!

• Example: Bread mould on old bread.

Animals (including you!) use this method:

1. Swallow food -> enters body.
2. Break it down internally with enzymes/teeth.
3. Absorb nutrients in the gut.

– Cow vs. Lion:

• Cow: Eats grass (stationary) -> flat teeth for grinding.
• Lion: Hunts deer (mobile) -> sharp teeth for tearing meat!

Parasites live **on or inside** a host, stealing nutrients:

• Cuscuta (Amar-bel): Wraps around plants -> sucks their sap.
• Tapeworms: Live in human intestines -> eat your food!

Warning: Parasites weaken hosts but rarely kill them instantly!

Every heterotroph’s body is designed for its food:

Organisms eat in *different ways* depending on their body design! Simple organisms (like tiny single-celled ones) eat with their *whole body*, while complex ones (like humans) have special organs (stomach, intestines).

Amoeba is a tiny water creature (like a squishy water balloon!). How it eats:

1. Grabs food with **pseudopodia** (stretchy arms) -> traps it in a **food vacuole**.
2. Digests food inside the vacuole (enzymes break it down).
3. Absorbs nutrients into the **cytoplasm** (cell jelly).
4. Spits out waste by pushing it out of its body!

Paramoecium (slipper-shaped cell) is fancier than Amoeba! It has:

• Cilia (tiny hairs) covering its body -> sweeps food into a **mouth pore**.
• Food vacuole forms -> digestion happens -> nutrients go to **cytoplasm**.
• Waste exits through a special spot (**anal pore**).

Why Cilia? They push food like a conveyor belt!

Every heterotroph’s body is designed for its food:

– Teeth crush food → small pieces.

– Saliva (spit) wets food + contains salivary amylase enzyme → breaks *starch* (roti/bread) into sugar.

– Tongue rolls food into a ball (bolus).

– Food ball (bolus) slides down via peristalsis → muscle squeezes like toothpaste from a tube!

– Works even if you’re upside down! 🙃

– Gastric glands release:

• HCl acid → Kills germs + turns food soupy.
• Pepsin enzyme → Chops *proteins* (eggs/dal).
• Mucus → Protects stomach from acid!

– Pyloric sphincter (gatekeeper!) → releases food slowly into intestines.

Food soup (chyme) gets processed:

1. Liver sends bile → Breaks *fats* into tiny drops (like soap on oil!) + neutralizes acid.
2. Pancreas sends enzymes:
   • Trypsin → Chops proteins.
   • Lipase → Chops fats.
3. Intestinal walls release enzymes → Food becomes:
   • Proteins → Amino acids
   • Carbs → Glucose
   • Fats → Fatty acids + Glycerol

🦠 Absorption:

– Villi (millions of finger-like bumps!) absorb nutrients into blood.

– Blood delivers nutrients to every cell! 💪

– Absorbs water → Poop solidifies.

– Waste exits via anus (controlled by anal sphincter).

1. Autotrophic vs. Heterotrophic Nutrition:

2. Raw Materials for Photosynthesis:

• CO₂ → From air (via stomata)
• Water → From soil (roots)
• Sunlight → Trapped by chlorophyll

3. Stomach Acid’s Role:

• Kills germs in food.
• Turns food liquidy.
• Activates pepsin enzyme.

4. Digestive Enzymes’ Function:

Chop complex food into tiny absorbable pieces:

• Carbs → Glucose
• Proteins → Amino acids
• Fats → Fatty acids + Glycerol

5. Small Intestine Design for Absorption:

• Villi → Increase surface area (like sponge!).
• Rich blood supply → Quick nutrient transport.
• Microvilli → Tiny hairs on villi (extra absorption!).

– Glucose (6-carbon sugar) breaks into pyruvate (3-carbon).

– Happens in cytoplasm (cell jelly) → needs *no oxygen*.

– *All living things do this!*

If oxygen is present:

• Pyruvate goes to mitochondria (cell powerhouses).
• Breaks into CO₂ + Water + 36 ATP coins 💰.
• Used by humans, animals, and plants during the day! 🌞

When oxygen is *absent*:

1. In Yeast:

   Pyruvate → Ethanol + CO₂ (called fermentation).

   – Makes bread rise! 🍞

2. In Muscles:

   Pyruvate → Lactic Acid (during push-ups/sprinting).

   – Causes muscle cramps! 💢

– Respiration releases energy → stored as ATP (Adenosine Triphosphate).

– Cells “spend” ATP for:

• Thinking 🧠
• Moving 💃
• Growing 📏

Plants “breathe” through stomata (leaf pores):

• Day: 🌞

  Photosynthesis > Respiration → Releases O₂ (we breathe this!).

• Night: 🌙

  Only respiration → Releases CO₂ (like animals!).

Follow an oxygen molecule:

1. Nostrils → Filtered by hairs/mucus.
2. Throat → Cartilage rings keep airway open.
3. Lungs → Air reaches alveoli (balloon sacs).
4. Alveoli → Oxygen diffuses into blood → caught by hemoglobin in RBCs.
5. Diaphragm (muscle) →
   • – Contracts (flattens) = Inhale 💨
   • – Relaxes (dome) = Exhale.

Blood = Plasma (55%) + Blood Cells (45%):

• Plasma:

  – Carries *dissolved* food (glucose), CO₂, waste (urea), salts → like a nutrient river! 🌊

• Red Blood Cells (RBCs):

  – Packed with hemoglobin → grabs O₂ in lungs → delivers to cells.

  – *Fun Fact:* Your body makes 2 million new RBCs *every second*! ⏱️

– 4 Chambers: 2 atria (entry rooms) + 2 ventricles (exit rooms).

– Double Pump:

• – *Right side:* Pumps O₂-poor blood → lungs 💙
• – *Left side:* Pumps O₂-rich blood → body ❤️

– Valves: Go “Lub-Dub” → prevent backflow!

– Platelets: Tiny cell fragments → form *clots* to seal cuts (like emergency road crews! 🚧).

– Fibrin: Sticky protein net → traps blood cells to form scabs.

Follow the blood’s journey through the heart:

Oxygen-Rich Blood Path (❤️):

1. Lungs → Left Atrium (thin-walled entry room).
2. Left Atrium squeezes → blood pushed into Left Ventricle (thick-walled exit room).
3. Left Ventricle PUMPS! → blood sent to entire body.

Oxygen-Poor Blood Path (💙):

1. Body → Right Atrium (entry room).
2. Right Atrium squeezes → blood pushed into Right Ventricle.
3. Right Ventricle PUMPS! → blood sent to lungs to grab oxygen.

– Ventricles have thick muscles → need power to pump blood far!

– Left ventricle = strongest → pumps blood to your toes! 👣

– Atria walls = thin → only push blood to ventricles (short distance).

– Tricuspid & Mitral valves → Between atria & ventricles.

– Pulmonary & Aortic valves → Between ventricles & arteries.

– “Lub-Dub” Sound:

• – *Lub* = Valves closing between atria/ventricles.
• – *Dub* = Valves closing to arteries.

1. You inhale → air reaches alveoli (millions of tiny balloons!).

2. Oxygen (O₂) crosses alveoli walls → enters blood.

3. Hemoglobin (in RBCs) grabs O₂ → becomes oxygenated blood (❤️ bright red!).

Your heart has 4 chambers to *separate* oxygen-rich and oxygen-poor blood:

• Right Side: Pumps deoxygenated blood (💙) → Lungs (to grab O₂).
• Left Side: Pumps oxygenated blood (❤️) → Body (to deliver O₂).

– Job: Carry oxygen-rich blood (except pulmonary artery) from heart → body.

– Walls: Thick + elastic → handle heart’s powerful pump 💥.

– Pressure: Blood spurts if cut! *(Don’t try this!)* 🚫

– Job: Bring oxygen-poor blood (except pulmonary vein) from body → heart.

– Walls: Thin → low pressure inside.

– Special Feature: Valves → stop blood from flowing backward (like one-way street signs! 🛑).

– Size: Microscopic → red blood cells squeeze through single-file!

– Walls: One-cell thick → easy exchange of:

• – O₂/food → out to cells 🍎
• – CO₂/waste → into blood 🗑️

Heart ❤️ → Artery (thick) → Arteriole (small artery) → Capillary (exchange) → Venule (small vein) → Vein (thin + valves) → Heart ❤️

1. Leak Alert! 🚑

You get a cut → blood vessel tears → platelets rush to the spot.

2. Sticky Patch! 🩸

Platelets clump together → form a temporary plug.

3. Net Trap! 🕸️

Platelets release chemicals → create fibrin (sticky net) → traps blood cells → forms a clot (scab).

– Prevents Blood Loss: Without platelets, a tiny cut could make you lose all your blood! 😱

– Saves Pressure: Clots keep blood pressure stable → heart pumps efficiently ❤️.

– Blocks Germs: Scabs shield wounds from bacteria 🦠.

1. Blood Leak! 🩸

At capillaries, plasma (blood liquid) leaks out → becomes tissue fluid around cells.

2. Cleanup Time! 🧹

This fluid:

• – Brings nutrients to cells.
• – Washes away waste/germs.

3. Lymph is Born! 💦

After cleaning, 90% of fluid returns to blood → 10% becomes lymph!

1. Fat Taxi! 🍟

Carries digested fat from intestines → to blood (bypassing liver!).

2. Fluid Recycler! ♻️

Drains excess fluid from tissues → back to veins → prevents swelling!

3. Germ Fighter! 🦠

Contains white blood cells → attacks infections!

1. Lymphatic Capillaries:

– Tiny tubes → suck up lymph from tissues (like straws!).

2. Lymph Vessels:

– Merge into larger tubes → have valves (like veins!) → drain into chest veins.

3. Lymph Nodes:

– Checkpoints that filter germs → swell when you’re sick!

1. Roots suck water + minerals (nitrogen, phosphorus) from soil.

2. Leaves make food (sugar) via photosynthesis.

3. But roots ≠ leaves! Tall trees need a delivery system for:

• – Water → Up to leaves ☀️
• – Food → Down to roots/stems/fruits ⬇️

– Structure: Dead, hollow tubes (like straws!).

– Job: Carry water + minerals **upward** from roots → leaves.

– Driver: **Transpiration** – sunlight evaporates water from leaves → pulls water up like a chain! 🔗

– Structure: Living tubes with sieve plates (like colanders!).

– Job: Carry sugary food (**sap**) **downward** from leaves → roots/fruits/storage.

– Driver: Pressure flow – leaves “push” sugar syrup to hungry parts. 🍯

Plants don’t need fast transport because:

• – They don’t move → low energy needs.
• – Many cells are dead (like wood!) → don’t “eat”.
• – Transport is slow but steady – perfect for their lifestyle! 🐢

– Structure: Interconnected dead tubes (vessels + tracheids) → form a continuous pipeline from roots → leaves.

– Job: Carry water + minerals UP ↑ against gravity!

– How it works:

1. Roots actively suck minerals from soil → minerals pile up inside root cells.
2. Water rushes into roots (to balance mineral concentration).
3. Creates root pressure → pushes water up xylem.

– When? Mainly at night when transpiration stops.

– Step 1: Sun heats leaves → water evaporates from stomata (leaf pores).

– Step 2: Evaporation creates suction → pulls water from xylem.

– Step 3: Water molecules stick together like a chain → whole column rises! 🔗

Besides moving water:

• 1. Cools Leaves: Like sweating cools you! ❄️
• 2. Delivers Minerals: Water = mineral taxi! 🚕
• 3. Keeps Plants Firm: Water pressure plumps up cells → no wilting! 💪

– Structure:

• – Sieve Tubes: Stacked cells with holes (like colanders!) → let sap flow.
• – Companion Cells: “Brainy helpers” that load/unload sugar using ATP energy! ⚡

– Job: Carry sugary sap (sucrose), amino acids, vitamins → to roots, fruits, buds.

Step-by-Step Food Journey:

1. Loading:

– Leaves make sucrose → pumped into phloem by companion cells (uses ATP!).

2. Water Rush:

– High sugar in phloem → sucks in water (osmosis) → creates high pressure. 💧

3. Flow:

– Sap squirts from high-pressure areas (leaves) → low-pressure areas (hungry roots/buds).

4. Unloading:

– Sugar removed at destination → water leaves → pressure drops.

Unlike xylem (gravity/transpiration), phloem:

• – Uses ATP to load sugar → active transport.
• – Adjusts flow based on plant’s needs (e.g., more sugar to fruits in summer!).

Unicellular organisms (like amoeba):

• – Waste (ammonia, CO₂) diffuses out → through cell membrane → into water.
• – No special organs needed!

Multicellular organisms (humans, animals, plants):

Need special organs because waste must travel far!

Plants remove waste differently:

• – Oxygen (from photosynthesis) → released through stomata! 🌿💨
• – Tannins, Resins → stored in leaves/bark → leaves fall to remove waste! 🍂
• – Gums → ooze out from stems (like mango tree sap!).

– Job: Filter blood 300x/day → remove urea (toxic waste from protein), extra salts, water.

– Location: Back of your belly (size: your fist!).

Each nephron works like a coffee filter:

1. Filtration:

– Blood enters capillary cluster → waste + water + good stuff (glucose) leak into Bowman’s capsule.

2. Re-absorption:

– Useful stuff (glucose, amino acids, 99% water) get sucked back into blood.

3. Urine Formation:

– Leftover liquid = pee (water + urea + salts).

1. Kidneys → Make urine.

2. Ureters (2 thin tubes) → Carry urine to bladder.

3. Bladder → Stores urine (stretchy bag → holds 400-600 ml!).

4. Urethra → Pee exits when you “go”!

– During photosynthesis, plants make oxygen (O₂) as a by-product → released through stomata!

– Twist: This “waste” is what we breathe! 💨

– Plants drink lots of water → excess removed via transpiration (leaf “sweat”).

– Bonus: Transpiration also cools leaves! ❄️

– Toxic wastes (tannins, oxalates) stored in old leaves → leaves turn yellow/orange → drop off!

– Autumn leaf fall = plant detox! 🍁

– Resins: Yellowish waste in pine trees → used to make turpentine!

– Gums: Gooey blobs on mango/cherry trunks → used in jellies and glue!

– Roots release wastes (salts, acids) into soil → absorbed by soil microbes.

– Example: Mustard plants release toxins to kill competing weeds! ☠️