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Lecture 1

Properties of Life：

1. Order – highly organized, made up of cell(s)

2. Sensitivity/response to stimuli

3. Reproduction

4. Adaptation – due to evolution by natural selection

5. Growth and development

6. Regulation

7. Homeostasis – the ability of an organism to maintain constant internal conditions

8. Energy processing

Levels of Biological Organization：

1. Atom：= smallest unit of matter  • Contains a nucleus surrounded by electrons

2. Molecule = cluster of at least 2 atoms held together by chemical bonds

3. Organelle = membrane-bound subcellular structure, Performs a specific function within a cell

4. Cell: the smallest unit that displays all the characteristics of life

5. Tissue: groups of similar cells carrying out the main function; 4 major tissue types = connective (eg. bone), epithelial (eg. skin), muscle, nervous

6. Organ: a collection of tissues that together provide a specific function

7. Organ System: several organs that work together to perform a specific function

8. Organism: an individual living thing

9. Population: all the individuals of a species living within a specific area

10. Community: all the living organisms of all the different species interacting in one area

11. Ecosystem: all the living(biotic) and non-living(abiotic) parts of a particular area

12. Biome: major ecosystem types

13. Biosphere: the highest level of organization

The Cell Theory

1. All organisms are made up of cells

2. Cells are the basic unit of life

3. All cells arise from pre-existing cells (added by Rudolf Virchow)

Unicellular vs. Multicellular Organisms

• Unicellular organism = all functions need to be carried out by the one cell

• Multicellular organism = many specialized cells that are dependent upon each other fororganism function and survival

Prokaryotic vs. Eukaryotic Cells

• 3 Domains of life (will cover next week in “Taxonomy”):

• 1. Bacteria, 2. Archaea, 3. Eukarya

• Bacteria and Archaea are made up prokaryotic cells

• Eukarya (animals, plants, fungi, protists) are made up of eukaryotic cells• Allcellshave4commoncomponents:

1. Plasma membrane - outer covering separating the cells interior from exterior environment

2. Cytoplasm – jelly-like region inside the cell

3. DNA – genetic material

4. Ribosomes – synthesize proteins

Plasma Membrane

• Surrounds cells to separate internal contents from external environment • Structure = aphospholipid bilayer with proteins embedded

• Phospholipid = composed of two fatty acid chains, a glycerol backbone, and a phosphate group

• Function = regulates the passage of substrates eg. ions, water

Cytoplasm

• Structure = made of gel-like cytosol

• Function = holds all the contents of a cell between the plasma membrane and the nuclearenvelope, such as organelles

Nucleus

• Structure = surrounded by a double membrane called the nuclear envelope

• houses the nuclear DNA (genetic material) in the cell in structures called chromosomes

• Function = protects DNA and controls all cell activities

• Information from DNA is used to make proteins

Endoplasmic Reticulum

• Structure = A network of flattened, interconnected membrane sacs

• Rough ER Function = protein synthesis, membrane synthesis

• Smooth ER Function = lipid synthesis, carbohydrate synthesis

Ribosomes

• Structure = made of ribosomal RNA and protein ; Do NOT have a membrane

• Function = carry out protein synthesis in 2 places

Golgi

• Structure = a stack of flattened membranous stacks called cisternae

• Function = sorting, tagging, packaging, and distribution of lipids and proteins

Mitochondria

• Structure = oval-shaped, double-membrane organelles

• inner layer has folds called cristae

• have their own ribosomes and DNA

• Function = cellular respiration (form ATP by breaking down glucose)

Lysosomes

• Structure = membranous sacs (single membrane) containing hydrolytic enzymes (very acidicpH inside)

• Produced by the Golgi apparatus

• Very uncommon in plants

• Function = break down waste products

• Destroy/recycle molecules, organelles and macromolecules

Cell Wall

• Structure = rigid covering outside the plasma membrane made mostly of cellulose

• Function = provides support, protection, and shape to the cell

Central Vacuole

• Structure = a large water-filled vacuole

• Takes up majority of plant cell

• Function = regulates cell water levels

Chloroplasts

Structure = have their own DNA and ribosomes

• Have inner and outer membranes

• Inside has interconnected and stacked membrane sacs called thylakoids

• Function = for photosynthesis

Cellular Respiration vs. Photosynthesis

• Plants are autotrophs – can make their own food

• Animals are heterotrophs – rely on other organisms for food

• Photosynthesis = light energy used to transform CO2 and water into glucose and oxygen• Cellular respiration = glucose is broken down to release energy in the form of ATP (for cell functions)

• Releases CO2 and water by-products

• Occurs in mitochondria

Lecture – 2

The Nature of Science：The systematic study of the structure and behaviour of the physical and natural world through observation & experiment

Principles of Science

• Goals: To understand reality

• Interested in FACTS – not opinions or beliefs

• Numerical information

• Any uncertainty is quantified (and shared openly)

Hypothesis = a suggested explanation for an event or observation

Scientific theory = a generally accepted explanation for a set of observations or phenomena supported by scientist

The scientific method is a method of research with defined steps that include experiments and careful observation The Scientific Method

Step 1: Make observations

Step 2: Ask a research question

Step 3: Formulate testable hypotheses

Step 4: Make predictions

Step 5: Design experiments to test hypotheses

Null vs. Alternate Hypotheses

• Null hypothesis (H0) = Statement that the independent variable will not have an effect on thedependent variable

• Alternate hypothesis (HA) = Statement that the independent variable will have an effect onthe dependent variable

Independent vs Dependent Variables

• Independent variable = The factor being manipulated by the researcher.

• Dependent variable = The variable that the researcher predicts will be affected and measuredto determine the effect (response variable)

A controlled experiment compares a treatment group to a control group；Set up your groups so that the ONE difference between them is your independent variable

Standardized variables = you should identify any variables other than the independent and dependent variables (i.e., external variables) that could influence the experiment

Replication = refers to the number of individuals in the treatment and control groups Evolution = a change in the heritable characteristics in a population over time

Character = an observable feature that can vary among individuals

Natural selection = one mechanism by which populations can evolve

Adaptation = an inherited trait that increases an individual’s probability of survival in a particular environment： structural，behavioural，and physical

Lecture 3 – Taxonomy

Biological species: A group of populations whose members have the potential to interbreed and produce viable, fertile offspring (in nature)

Taxonomy: A scientific discipline for organisms to be named, defined, and classified

Practical use: We organize living things into categories to help make sense of the vast diversity • Carolus Linnaeus is the “Father of Taxonomy”, Developed both hierarchical classification and binomial nomenclature

Linnaean Taxonomic System: is organized into a hierarchy of taxa

• Taxon (plural taxa) is a general term for any level of the hierarchy

• Species are grouped into increasingly larger and more inclusive groups

• Usually based on morphological similarities

Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species

Binomial Nomenclature: two-part format for assigning scientific names to species

Phylogeny = the evolutionary history of a species

Systematics = a discipline focused on classifying organisms and determining their evolutionary relationships

Darwin’s Influence on Classification

• Darwin proposed that all living species are descended from a series of common ancestors

• Similarities arose through inheritance of characters from shared ancestors

• Differences arose through evolution and adaptation to different environments• He called this process evolution

• Darwin envisioned this process as a tree, with the trunk representing a common ancestor andthe branches its many descendants

• Systematics applies the concept of descent with modification to the classification of livingthings

 

Natural vs. Artificial Classification Systems

• Systematics is a classification system because it groups living things into phylogenies based onreal evolutionary relationships

• Systems that classify organisms based on a few morphological characters are consideredclassification systems because similar morphological traits may not reflect actual relatedness • The Linnaean taxonomy is an artificial classification system because it is based on morphological traits (this is our current classification system)

Misclassifications happen when:

• Natural selection removes unfavourable traits from populations

• Similar traits arise independently due to adaptation to similar environments

3 Domains of Life

1. Bacteria = prokaryotes

2. Archaea = prokaryotes

3. Eukarya = eukaryotes (includes Fungi, Plantae, Animalia, Protista*)

1. From the origin of Earth ~4.6 bya came the oldest prokaryotes ~3.5 bya: Likely our single common ancestor of the 3 domains of life

2. Oxygen levels started to increase, allowing first eukaryotes to appear ~1.8 bya

3. Algae and invertebrate animals evolve ~600 mya

4. The Cambrian explosion led to an increase and colonization of land ~450-500 mya

Lecture 4

Prokaryotes: Masters of Adaptation - The first organisms to inhabit Earth (~3.5 bya)

• Live in some crazy places due to their ability to autotroph

• Oldest group of organisms on Earth; Include all four nutritional modes; Adapted to EVERYhabitat on Earth; Immense genetic diversity; Reproduce rapidly and are extremely abundant; Are extremely important for the function of our biosphere

Prokaryote ecological roles:

1. Pathogens – disease causing, e.g. strep throat, salmonella, Lyme disease

2. Chemical cycling – heterotrophic bacteria act as decomposers by feeding on and breaking down decaying bodies of plants and animals and releasing the inorganic molecules so other organisms can re-use them

3. Mutualistic associations with other organisms, e.g. bacteria in your intestines break down organic molecules that you and the bacteria can use Prokaryote biotechnology roles:

1. Food Production = we use bacteria in the production of many foods including dairy products such as yogurt and cheese

2. Drugs = prokaryotes are both harmful and helpful to human health

3. Bioremediation = Under normal (healthy) circumstances, the commensal bacteria in our gut out-compete with the harmful intruders for resources

Bacteria vs Archaea Similarities:

• Cell wall

• Ribosomes

• Single circular chromosome

• Lack nucleus• Lack organelles Differences:

• Composition of cell wall

• DNA structure (some archaea have histones, introns)

• Different proteins used to copy DNA

• Different start codon for building proteins

Even though Bacteria and Archaea are both prokaryotes, Archaea is more closely related to Eukarya! (more genetic similarities)

Endosymbiosis Theory = Mitochondria arose first from aerobic

4. heterotrophic prokaryote being ”engulfed” by a larger anaerobic prokaryote • Chloroplasts arose later from photosynthetic prokaryote being engulfed. Since all eukaryotic cells have mitochondria, thought to been absorbed first

5. “Host” cells and “endosymbionts” now completely interdependent on each other and could not survive apart

Protists = eukaryotes that are not fungi, plants, or animals

• Majority are eukayotes

• Other than these 2 features, protists have very little in common

• Scientists realized there is too much diversity within one kingdom – now separated intomultiple kingdoms

• Classification: animal-like, plant-like, and fungi-like

 

Fungi

• A true eukaryotic kingdom

• Chemoheterotrophs

• Release enzymes and digest food outside body and absorb nutrients

• Multicellular (except yeast - unicellular)

• Cell walls composed of glucans, chitin and glycoproteins

• Hyphae = an underground network of branched filaments• Function like plant roots; they absorb nutrients and water from surroundings

• Mushrooms = some fungi form these above-ground • Spore-producing reproductive structures

Fungi Ecological Roles

• Decomposition = break down dead organic materials and release nutrients back to ecosystem

• Predators = capture, kill and digest nematode worms

• Parasitism = an interaction that benefits the survival and/or reproduction of one species, whilecausing harm to the other

Fungi biotechnology roles:

Food = mushrooms and truffles, yeast for bread and alcohol Antibiotics = penicillin, first antibiotic, made by fungi

Lecture 5 – the greening of the earth

Plants = eukaryotes which are multicellular, photoautotrophs, and cell walls made of cellulose.

Plants vs. Protist Differences:

• All plants are multicellular; Algae can be unicellular, colonial or multicellular

• Most plants live on dry land; Algae live in aquatic or moist terrestrial habitats • Plants have awaxy cuticle; Algae do not

• Most plants have roots, stems, leaves, & vascular tissue; Algae do notBasic resources:

For photosynthesis: water, light, carbon dioxide

For cellular respiration: O2

To make DNA, proteins, lipids: Mineral nutrients

Compare water and land as habitats for plants in terms of: (a) availability of nutrients and light (b) support (c) reproduction and dispersal.

(a) The water plants can access light but only on the near surface, whereas, the land plantscan gain brighter and infiltered sunlight.

The water plants can take up nutrients directly from the water via diffusion, but they are limited amounts of dissolved O2, CO2, and minerals; whereas, the habitats of land plants, and soil, are rich in nutrients.

(b) The water plants are surrounded and supported by water, whereas, the land plants lackstructural support against gravity.

(c) The water plants’ gametes are released directly into the water for easy dispersal,whereas, the land plants’ reproduction needed to be altered to prevent spores from drying out.

Plant system: shoot system(stems+leaves)+ root system Root function:

allow plants to absorb nutrients from the soil anchor plants to allow them to grow taller Stem function:

The primary function is to raise and support the photosynthetic surface to capture light Leaf function:

The primary function is light capture and photosynthesis Tissue system:

Dermal tissue system: the outer covering of the plant (outer)

Epidermal cells — simple cells on the surface of all plant structures– secrete waxy cuticles.

Guard cells – control opening and closing of stomata

Root hairs – responsible for absorption, and increasing surface area. Also, contribute to anchoring plants.

Ground tissue system: functions in storage, photosynthesis, and support. (mid) Parenchyma cells:  1. living cells   2. thin and flexible  3. perform most metabolic 4. functions of the plant (including photosynthesis)

Collenchyma cells: 1. living cells   2. walls irregularly thickened(deposits of cellulose)   3. provides flexible support

Sclerenchyma cells: 1. dead at maturity   2. REALLY rigid cells for support

（have secondary cell walls）

Vascular tissue system: the transport system of the plant (inner)

Xylem：

I. Tracheids (water-conducting cells): 1. cells dead at maturity 2. long,thin and tapered cells  3. lignified secondary cell walls  4. pits in tracheids are areas where there is no   5. secondary cell wall. Water moves from cell to cell through the pits【vascular plants】

II. Vessel elements (water-conducting cells): 1. Wider and shorterthan tracheids 2. Connected end to end lengthwise (form long tubes)  3. Have both pits and large perforations at cell ends for water flow  4. More efficient at water transport than tracheids  5. Cells dead at maturity【most angiosperms and a few gymnosperms and seedless vascular plants.】

phloem

I. Sieve tube elements (sugar-conducting cells): transport organic molecules (sugarmainly) dissolved in the water alive at maturity, but no secondary walls, nucleus, ribosomes or vacuole plasma membrane is functional connect to each other by sieve plates so fluid can move between them

II. Companion cells: alive at maturity; possess all the typical organelles of a plant

cell; connected to sieve tube elements by plasmodesmata Cell Walls: primary and secondary cell walls All plant cells have a primary cell wall.

Lecture 5 – the greening of the earth

Plants = eukaryotes which are multicellular, photoautotrophs, and cell walls made of cellulose.

Plants vs. Protist Differences:

• All plants are multicellular; Algae can be unicellular, colonial or multicellular

• Most plants live on dry land; Algae live in aquatic or moist terrestrial habitats • Plants have awaxy cuticle; Algae do not

• Most plants have roots, stems, leaves, & vascular tissue; Algae do notBasic resources:

For photosynthesis: water, light, carbon dioxide

For cellular respiration: O2

To make DNA, proteins, lipids: Mineral nutrients

Compare water and land as habitats for plants in terms of: (a) availability of nutrients and light (b) support (c) reproduction and dispersal.

(a) The water plants can access light but only on the near surface, whereas, the land plantscan gain brighter and infiltered sunlight.

The water plants can take up nutrients directly from the water via diffusion, but they are limited amounts of dissolved O2, CO2, and minerals; whereas, the habitats of land plants, and soil, are rich in nutrients.

(b) The water plants are surrounded and supported by water, whereas, the land plants lackstructural support against gravity.

(c) The water plants’ gametes are released directly into the water for easy dispersal,whereas, the land plants’ reproduction needed to be altered to prevent spores from drying out.

Plant system: shoot system(stems+leaves)+ root system Root function:

allow plants to absorb nutrients from the soil anchor plants to allow them to grow taller Stem function:

The primary function is to raise and support the photosynthetic surface to capture light Leaf function:

The primary function is light capture and photosynthesis Tissue system:

Dermal tissue system: the outer covering of the plant (outer)

Epidermal cells — simple cells on the surface of all plant structures– secrete waxy cuticles.

Guard cells – control opening and closing of stomata

Root hairs – responsible for absorption, and increasing surface area. Also, contribute to anchoring plants.

Ground tissue system: functions in storage, photosynthesis, and support. (mid) Parenchyma cells:  1. living cells   2. thin and flexible  3. perform most metabolic 4. functions of the plant (including photosynthesis)

Collenchyma cells: 1. living cells   2. walls irregularly thickened(deposits of cellulose)   3. provides flexible support

Sclerenchyma cells: 1. dead at maturity   2. REALLY rigid cells for support

（have secondary cell walls）

Vascular tissue system: the transport system of the plant (inner)

Xylem：

I. Tracheids (water-conducting cells): 1. cells dead at maturity 2. long,thin and tapered cells  3. lignified secondary cell walls  4. pits in tracheids are areas where there is no   5. secondary cell wall. Water moves from cell to cell through the pits【vascular plants】

II. Vessel elements (water-conducting cells): 1. Wider and shorterthan tracheids 2. Connected end to end lengthwise (form long tubes)  3. Have both pits and large perforations at cell ends for water flow  4. More efficient at water transport than tracheids  5. Cells dead at maturity【most angiosperms and a few gymnosperms and seedless vascular plants.】

phloem

I. Sieve tube elements (sugar-conducting cells): transport organic molecules (sugarmainly) dissolved in the water alive at maturity, but no secondary walls, nucleus, ribosomes or vacuole plasma membrane is functional connect to each other by sieve plates so fluid can move between them

II. Companion cells: alive at maturity; possess all the typical organelles of a plant

cell; connected to sieve tube elements by plasmodesmata Cell Walls: primary and secondary cell walls All plant cells have a primary cell wall.

Chap.6

1. Compare and contrast primary and secondary cell walls of vascular plants in terms of location, structure and function. Primary cell wall = in all plant cells

• Secreted by the plasma membrane

• Composed of cellulose

• Provides protection and support to the cell

Secondary cell wall = only in some cells

• Secreted by the plasma membrane after the primary wall • Composed of cellulose and lignin

• Adds strength and rigidity (eg. in wood and bark)

2. Define turgor pressure and explain how it contributes to support in plants.

Turgor Pressure = the plasma memcrane exerted by water inside of the cell against the primary cell wall

• When the area around the cell (eg. rainwater) has a higher solute concentration than inside ofthe cell, water will rush IN

• An animal cell with no cell wall will burst

• A plant cell’s cell wall prevents it from bursting,causing the cell to be turgid

• This is the healthy state of a plant cell!

3. Describe the structure and functions of the root system and shoot system of a vascular plant.

1. Root System = responsible for absorbing water and nutrients from the soil

• Organ involved – root

2. Shoot System = responsible for photosynthesis

• Organs involved = leaf and stem

5. Describe the location of meristematic tissue in plants and explain its significance to the primary growth of the root and shoot system Plant growth:  meristems and primary growth

Meristems are areas of rapid cell division that facilitate growth in plants; Meristem cells have the potential to become any cell type (similar to stem cells in animals) Primary growth = elongation of shoots and roots at the tips; Primary growth occurs through apical meristems; Apical meristems produce primary xylem and primary phloem

6.Describe secondary growth and explain how it contributes to mechanical support.

Secondary Growth：

Secondary growth = increase in the diameter of stems and roots in woody plants Secondary growth occurs due to division of cells in lateral meristems

The vascular cambium is a lateral meristem that produces secondary xylem and secondary phloem which increases the diameter of woody stems

Bio – lecture 7

1. Describe the distinguishing characteristics of animals.

Eukaryotic

Multicellular

Heterotrophs

No cell wall

3. Outline a hypothesis for the origin of animals from ancient animal-like protists.

Hypothesis: evolved from a group of colonial protists called choanoflagellates, reasons:

1. Eukaryotes = choanoflagellate cells and collar cells of sponges very similar

2. Additional animal similarity = collar cells have been found in other animal phyla, but not inplants or fungi

3. DNA = high overlap (similarity) between some choanoflagellate and animal genes

4. Discuss the following features of animal evolution: (a) radial and bilateral symmetry (b) a gutwith one opening and a gut with two openings (c) acoelomates and coelomates (d) differences in structural complexity.

(a) Radial symmetry = does not have a right/left side (eg. sea stars) ; Bilateral symmetry = have right/left sides (eg. humans)

(b)Gastrovascular cavity = gut with one opening. Food is ingested and waste is excreted via one opening ; Alimentary cavity = gut with two openings

(c) Protostome development = the mouth develops from the blastopore (“mouth first”);

Deuterostome development = the anus develops from the blastopore (“mouth second”) (d)Endoskeleton = skeleton that consists of hard, mineralized structures located within the soft tissue of organisms ; Exoskeleton = external skeleton that consists of a hard encasement on the surface of an organism; Hydrostatic skeleton = a flexible skeleton supported by fluid pressure

5. Define coelom and identify phyla which possess this feature.

Definition: the body cavity in metazoans, located between the intestinal canal and the body wall. Phyla: Suspension feeders – eat what pass through their cavity 6. Define gastrovascular cavity.

The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Coelenterates or cnidarians and Platyhelminthes. The cavity may be extensively branched into a system of canals.

7. Distinguish between exoskeleton and endoskeleton.

Endoskeleton = skeleton that consists of hard, mineralized structures located within the soft tissue of organisms ; Exoskeleton = external skeleton that consists of a hard encasement on the surface of an organism;

7. Analyze and interpret a phylogenetic tree of animal phyla.

Older phylogenies were based on similarities in morphology and development patterns; Current

trees are based more on molecular (DNA) similarities, evolutionary relationships Characteristics:1. Symmetry 2. Tissues 3. Body Cavities 4. Digestive Cavities 5.

Development 6. Skeleton

8. Describe the major characteristics of the following animal phyla:

(a) Porifera (b) Cnidaria(c) Platyhelminthes(d) Nematoda (e) Mollusca (f) Annelida (g) Arthropoda (h) Echinodermata (i) Chordata.

Porifera: Asymmetric; No tissues/organs; No body cavity; No digestive cavity; N/A; Hard spicules or soft spongin (a primitive endoskeleton)

Cnidaria: Radial symmetry; Diploblastic; No body cavity; Gastrovascular cavity; N/A;

Hydrostatic skeleton

Platyhelminthes:Bilateral symmetry; Triploblastic; Compact coelom; Gastrovascular cavity;

Protostome development; Hydrostatic skeleton

Nematoda: Bilateral symmetry; Triploblastic; Hemocoel; Alimentary cavity; Protostome development; Hydrostatic skeleton AND cuticle (an exoskeleton)

Mollusca: Bilateral symmetry; Triploblastic; Coelom; Alimentary cavity; Protostome development; Hydrostatic skeleton

Annelida: Bilateral symmetry; Triploblastic; Coelom; Alimentary cavity; Protostome development; Hydrostatic skeleton

Arthropoda: Bilateral symmetry; Triploblastic; Coelom; Alimentary cavity; Protostome development; Exoskeleton

Echinodermate: Larva bilateral symmetry; adult radial symmetry; Triploblastic; Coelom;

Alimentary cavity; Deuterostome development; Endoskeleton

Chordata: Bilateral symmetry; Triploblastic; Coelom; Alimentary cavity; Deuterostome development; Endoskeleton

9. Distinguish between the following classes of vertebrates: (a) ray-finned fish (b) amphibians (c) reptiles (including birds) (d) mammals. (a) Most familiar fish species Characteristics:

Fins – supported by bony rays

Gills – breathing in water

Bony scales – protection

(b)Frogs (tailess), salamanders (tails), caecilians (legless) Characteristics:

Most amphibious

Conduct some gas exchange across skin

Egg – no shell (not amniotic)

(c)Snakes, turtles, lizards, crocodiles, and birds!

Characteristics：

Scales made of keratin

Egg shell (often soft)

Ectothermic – internal temperature matches temperature of surroundings

(d)Monotremes, Marsupials, Eutherians (placental) Characteristics:

Mammary glands – produce milk

Hair and fat layer

Specialized teeth Endothermic

Bio – Lecture 8

1.Define the following: (a) ingestion (b) digestion (c) absorption (d) elimination.

(a) how the animal eats/feeds

(b) process of breaking down food into smaller molecules we can use

(c) the cells take up (absorb) the small molecule nutrients

(d) undigested material passes out of the digestive system and removed from the body

2. Distinguish between extracellular and intracellular digestion.

Intracellular digestion occurs inside cells food particles are golf by endocytosis which is the uptake of biological molecules DIA for the nation of food vacuoles by plasma membrane

Extracellular digestion occurs outside of cells, in compartments that are continuous outside of an animal's body. Enzymes and chemicals and secreted into the gastrovascular cavity or gut.

3. Discuss the significance of the evolutionary trend from intracellular to extracellular digestion.There is a trend in animal evolution toward increasing dependence on extracellular digestion. I almost went from intracellular digestion which absorbs nutrients into individual cells to extracellular digestion which transfer the digestive system on the inside of the organism allowing more food to be processed for a longer amount of time acquiring more nutrients in the end and making the most of the food

4. (a) Describe the location, structure and function of the following in humans:

(i) oral cavity (ii) esophagus (iii) stomach (iv) small intestine (v) large intestine (vi) liver (vii) gall bladder (viii) pancreas.

(b) Relate the structure of these digestive organs to their function.

(i)Oral cavity

–Tongue moves food around

–Teeth: used for chewing

–Salivary glands: release enzymes that begin breakdown of carbohydrates

(ii)Esophagus

—Passage between mouth and stomach

—Food (bolus) moved by muscle contractions called peristalsis

(iii)Stomach

-Rugae: folds in stomach lining enable expansion of stomach to store large quantities of food.

-pH of gastric juice is ~2, acidic enough to dissolve iron nails!

-Contractions of surrounding muscles churn food in acid and digestive enzymes, creating chyme

(iv)Small intestine

- Chyme enters through pyloric sphincter

- Most digestion is completed in the first segment of the small intestine, theduodenum

(v)large intestine

- Fermenting chamber containing mutualistic bacteria

- Feces become more solid as they move through the colon

(vi)liver: produces biles

(vii) gall bladder: concentrates and stores it

- Bile begins the breakdown of fats

- Emulsifier, the effect of dish detergent on oil

(viii) Pancreas

– secretes pancreatic juice into the duodenum through the pancreatic duct

5. Distinct the mechanical digestion and chemical digestion.

Mechanical digestion: physical breakdown of food into smaller pieces.

Chemical digestion: chemical breakdown of large molecules in food to smaller compounds

6. Compare and contrast the digestive systems of herbivores and carnivores and relate thedifferences to their respective diets.

Herbivores have much bigger is cecum then carnivores to digest cellulose large expandable stomachs are more common in carnivore so they can eat lots of prey at once

Bio – Lecture 9 biomes and nutrients

1.Define the terms ecology, community, ecosystem and biome.

Ecology = the scientific study of relationships between organisms and their environments

Community = all of the living organisms of all the different species interacting in one area

Ecosystem = all the living (biotic) and non-living (abiotic) parts of a particular area

Biome = Major ecosystem types

3. Distinguish between organic and inorganic compounds.

Organic Molecules = associated with living things

• Can contain atoms like oxygen, nitrogen

• Mostly contain Carbon-Hydrogen bonds, eg. glucose, fatty acids, DNA

Inorganic Molecules = from non-living sources

• Do not contain Carbon-Hydrogen bonds, eg. CO2, ammonia, nitrate

4. Identify two major functions of organic compounds and identify the source of these compounds for both autotrophs and heterotrophs.

Chemoheterotrophs = organic molecules provide us with both our organic source and our inorganic source (for cell respiration)

• Break them down to produce ATP (chemical energy)

• Recombine the carbons into new organic compounds (protein, lipids, nucleic, acids,carbohydrates)

Photoautotrophs = use CO2, water, and sunlight energy to make organic compounds (sugars) • But they ALSO break down organic compounds to produce ATP and recombine carbons into new organic compounds

5. Define biogeochemical cycle and outline the main components.

Biogeochemical Cycles = nutrient cycles

• They involve the transfer of nutrients between biotic and abiotic components of theenvironment

• Only limited amounts of molecules, so need to be recycled

6. Explain the significance of the elements carbon and nitrogen to living organisms and outline the major steps in the cycling of these elements in the biosphere.

Carbon Cycle: The cycling of carbon between the biotic and abiotic worlds is accomplished mainly by the reciprocal metabolic processes of photosynthesis and cellular respiration.

1. Carbon in the atmosphere 2.Photosynthesis. 3. Consumers eat 4. producers utilize. 5. Decomposers. 6. Volcanic activity and humans burning fossil fuels

Nitrogen: a key building block of DNA, protein, chlorophy l, and many biomolecules; one of the limiting factors for plant growth

1. Ammonification. 2. Nitrification. 3. Assimilation.

7. Explain, using examples, the impact humans have made on biogeochemical cycles.

• Humans release excess nitrogen into the environment via burning fossil fuels and use ofnitrogen-containing fertilizers in agriculture

• Increased levels of non-N2 nitrogen in the atmosphere: nitric acid (HNO3) can cause acid rain;nitrous oxide (N2O) is a greenhouse gas

• Eutrophication: excess nitrogen—containing fertilizer washed into waterways cause algaeovergrowth