Biology: Cellular Processes, Photosynthesis, and Nutrition Key Concepts

Basic nutrition

All organisms must acquire nutrients and convert them into ATP (energy) and structural molecules

Cellular respiration

Process that converts glucose, amino acids, and fatty acids into ATP

Location of cellular respiration (eukaryotes)

Mitochondria

Cellular respiration occurs in

Both autotrophs and heterotrophs

Cellular respiration purpose

To harvest biochemical energy and produce ATP

Cellular respiration equation

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Photosynthesis

Process that converts light energy into chemical energy (glucose)

Photosynthesis location (eukaryotes)

Chloroplasts

Photosynthesis location (prokaryotes)

Folded plasma membrane

Photosynthesis inputs

CO2, H2O, light

Photosynthesis outputs

Glucose and O2

Photosynthesis equation

6CO2 + 12H2O + light → C6H12O6 + 6H2O + 6O2

Autotroph

Organism that produces its own food (photosynthesis)

Heterotroph

Organism that must consume other organisms for energy

Order of plant processes step 1

Roots absorb water

Order of plant processes step 2

Xylem transports water to leaves

Order of plant processes step 3

CO2 enters leaves through stomata

Order of plant processes step 4

Chloroplasts perform photosynthesis to make sugar

Order of plant processes step 5

Phloem transports sugar to roots

Order of plant processes step 6

Root cells perform cellular respiration to make ATP

Order of plant processes step 7

ATP powers root growth and cell division

Macronutrients

Nutrients needed in large amounts

Examples of macronutrients

C, H, O, N, P, K, Ca, Mg, S

Micronutrients

Nutrients needed in small amounts

Examples of micronutrients

Fe, Mn, Cu, Zn

Magnesium function in plants

Component of chlorophyll

Magnesium deficiency result

Reduced photosynthesis due to lack of chlorophyll

Nitrogen importance

Needed for proteins and DNA

Atmospheric nitrogen

Exists mostly as N2 gas

Problem with N2

Cannot be used directly by plants

Usable nitrogen forms

NH3 (ammonia) and NO3⁻ (nitrate)

Nitrogen fixation

Conversion of N2 into usable forms by bacteria

Carnivorous plant environment

Nitrogen-poor, acidic soils (bogs)

Carnivorous plant adaptation

Digest insects to obtain nitrogen

Parasitic plants

Extract carbohydrates from host phloem

Parasitic plants additional effect

Also steal water and minerals from xylem

Animal nutrition type

Heterotrophic

Filter feeding

Straining small organisms from water

Deposit feeding

Consuming detritus from substrate

Fluid feeding

Sucking fluids like blood or sap

Bulk feeding

Eating large pieces of food

Humans feeding type

Bulk feeding

Incomplete digestive system

One opening for ingestion and waste

Complete digestive system

Two openings (mouth and anus) allowing one-way flow

Advantage of complete digestive system

Specialization of regions for digestion

Transport needs in organisms

Water, nutrients, gases, wastes, heat, hormones

Passive transport

Movement down gradient without energy

Active transport

Movement against gradient using ATP

Molecules that diffuse directly

O2 and CO2

Molecules requiring transport proteins

Glucose and amino acids

Diffusion

Movement from high to low concentration

Osmosis

Water movement toward higher solute concentration

Plant water transport direction

One-way from roots to leaves

Plant sugar transport direction

Bidirectional between sources and sinks

Source (phloem)

Tissue that produces sugar (leaves)

Sink (phloem)

Tissue that consumes or stores sugar (roots, fruits)

Xylem

Transports water and minerals upward

Phloem

Transports sugars throughout plant

Transport pathway 1

Through cell walls (apoplast)

Transport pathway 2

Through plasmodesmata (symplast)

Transport pathway 3

Across membranes (transmembrane route)

Casparian strip

Waterproof barrier in endodermis

Function of Casparian strip

Forces selective uptake through cells

Transpiration

Evaporation of water from stomata

Result of transpiration

Creates tension pulling water upward

Cohesion

Water molecules stick to each other

Adhesion

Water sticks to xylem walls

Transpiration pull

Main force moving water in plants

Root pressure

Upward push from roots due to ion uptake

Aquaporins

Proteins that facilitate water movement

Stomata

Openings that allow gas exchange

Guard cells

Control opening and closing of stomata

Cuticle

Waxy layer that reduces water loss

Plant gas exchange challenge

Balance CO2 intake with water loss

Solution to gas exchange challenge

Stomata and cuticle

Gas exchange goal

O2 in, CO2 out

Diffusion rate depends on

Distance, surface area, concentration gradient

Direct diffusion

Gas exchange across body surface

Organisms using direct diffusion

Porifera, cnidaria, flatworms, nematodes

Tracheal system

Network of tubes delivering air directly to tissues

Spiracles

Openings for air entry in insects

Limitation of tracheal system

Inefficient for large organisms

Gills

Structures for gas exchange in water

Gill structure

Filaments with lamellae

Lamellae function

Increase surface area for diffusion

Countercurrent exchange

Water and blood flow in opposite directions

Benefit of countercurrent exchange

Maintains concentration gradient

External gill disadvantage

Fragile and increases drag

Lungs

Internal gas exchange organs

Alveoli

Tiny sacs that increase surface area

Alveoli structure

One cell thick with many capillaries

Number of alveoli in humans

About 300 million

Amphibian lungs

Simple sacs with limited surface area

Cutaneous respiration

Gas exchange through skin

Amphibian adaptation

Use both lungs and skin

Mammalian breathing

Negative pressure breathing

Mechanism of inhalation

Rib cage expands, diaphragm contracts

Mechanism of exhalation

Muscles relax and air is pushed out

Bird lungs airflow

One-directional

Bird lung advantage

Maximizes oxygen extraction