1st Semester 59 - BIOLOGY JUNCTION

Food Testing

Chemical Tests for Nutrients in Food

INTRODUCTION:

Cells are made up of small molecules like water; ions such as sodium and magnesium, and large organic molecules. There are four important types of large organic molecule in living organisms — proteins, carbohydrates (sugars & starches), lipids (fats), and nucleic acids. Proteins, carbohydrates, and fats serve as nutrients in the food that we eat.

In this experiment you will evaluate the nutrient content of unidentified food samples. You will use chemical reagents to test the unknown for specific nutrients. By comparing the color change a reagent produces in the unknown with the change it produces in the known nutrient, you can estimate the amount of that nutrient. Use small samples.

MATERIALS:

400-ml beaker
Hot plate
8 test tubes
Test tube rack
4 medicine droppers
Glass stirring rod
Tongs
Several unknown food substances
Glucose
Cornstarch
Non-fat dry milk
Lard
Distilled water
Benedict’s solution
Iodine-potassium iodide solution
10% aqueous sodium hydroxide solution
0.5% Copper sulfate solution
Sudan III solution

PROCEDURE:

Monosaccharide (simple sugar) test

1. Fill a 400-ml beaker to about 300 ml with water and heat on the hot plate.

Be sure to label all test tubes.

2. Place pea-sized portions of glucose and the unknown substance you are testing in separate test tubes. Add about 2.5 ml of distilled water and 10 drops of Benedict’s solution to each test tube. Mix with a stirring rod, or holding the tube between the thumb and index finger of one hand, thump it with the middle finger of the other hand to mix.

REMEMBER: If you use a stirring rod, wash it after every use, so you won’t contaminate one solution with another.

3. When the water boils, use tongs to place the test tubes in the water bath. Leave the test tubes in the water bath for 10 minutes.

Do not let the water bath boil hard. Control the boiling by turning the hot plate on and off as needed.

4. Remove the test tubes with tongs and place the tubes in a test tube rack. Unplug the hot plate to cool. When the tubes cool, an orange or red precipitate will form if large amounts of glucose are present. Small amounts of glucose will form a yellow or green precipitate. Record your observations in the DATA TABLE.

Polysaccharide complex sugar) test

5. Place cornstarch in a clean test tube and some of the unknown substance in another. Use a clean dropper to add 10 drops of iodine-potassium iodide solution to each test tube. Observe the results and record in the DATA TABLE.

Protein test

6. Place non-fat dry milk in a clean test tube and some of the unknown in another. With a clean dropper slowly add an amount of sodium hydroxide solution about equal to the amount of the milk sample, and mix carefully. Then add 10 drops of copper sulfate solution one drop at a time. Mix gently between drops. Observe the results and record in the DATA TABLE.

7. Repeat step 6 with the unknown substance.

Lipid test

8. Place a small piece of lard in a clean test tube and some of the unknown in another. Use a clean dropper to add 10 drops of Sudan III solution to each test tube. Mix well, observe and record your results in the DATA TABLE.

DATA TABLE:

Monosaccharide test		Polysaccharide test
Mark your results in the appropriate boxes. Indicate relative amount by H for high, M for medium, L for low, or 0 for none.
SUBSTANCE:	RELATIVE AMOUNT:	SUBSTANCE:	RELATIVE AMOUNT:
Unknown	Unknown
Glucose	Corn starch

Protein test		Lipid test
SUBSTANCE:	RELATIVE AMOUNT:	SUBSTANCE:	RELATIVE AMOUNT:
Unknown	Unknown
Non-fat dry milk	Lard

CONCLUSIONS:

Question 1 . What is the main nutrient in the unknown?

Question 2. What are the controls in this investigation?

Examples of Organic Models





BACK

Evolution & Phylogeny AP Study Guide

Unit 6 Evolution & Phylogeny Study Guide
Be able to give an example of an idea that Charles Darwin borrowed from Thomas Malthus Know some anatomical structures that would be homologous to the wing of a bat Know what important information was unavailable to Darwin in the mid-nineteenth century when he formulated his theory of evolution Know the name of Darwin’s 1859 publication Be able to explain all parts of the Darwin-Wallace theory of natural selection Be able to explain how phylogenetic relationships are determined for closely related species Be able to differentiate between analogous & homolgous structures Know the requirements for the maintenance of Hardy-Weinberg equilibrium Be able to use the Hardy-Weinberg equation to determine allele frequencies and genotypic frequencies Be able to describe and give an example of a cline Be able to explain the bottleneck effect Know what process creates new alleles and serves to balance natural selection Be able to explain & give an example of genetic drift Know what is meant by the “gene pool” Know the major divisions of geologic time Be able to give several examples of fossil types Be able to explain binomial nomenclature Be able to list in order the major taxonomic categories Know what individuals in a population would most often carry copies of harmful recessive alleles Be able to explain & give an example of hybrid sterility Be able to explain & give an example of ecological isolation of species Know what polyploidy is & how it can cause rapid speciation Know the effect of mitosis & meiosis on allelic frequencies in nature Be able to explain the effect on alleles when new members move into a population Know the difference in prezygotic & postzygotic barriers Be able to name & and give examples of prezygotic and postzygotic barriers Be able to explain & give examples of mechanical and behavioral isolation Know the difference between sympatric isolation and allopatric isolation Be able to explain why such a great diversity of life exists on the Hawaiian & Galapagos Islands Be able to tell the difference between anagenesis & cladogenesis Know what taxonomic level can exist as a discrete unit in nature Know what taxonomic unit would show the most genetic variation Be able to explain & give an example of adaptive radiation Be able to determine the age of a fossil using the half-life of carbon-14 Know what major evolutionary episode occurred closely with the formation of Pangaea Be able to explain phylogeny Know the significance of the asteroid hypothesis Be able to explain & give examples of divergent & convergent evolution

Evolution Answers

Evolution Answers

1. In biological terms, what is a species? a group of organisms that are similar in form and structure
  a group of organisms that can interbreed
  a group of organisms that share common features
  a group of organisms that have live in the same habitat
2. What is the Scala Naturae? an idea proposed by Darwin that suggests that all organisms share a common ancestor
  an idea proposed by Plato that suggests organisms are all evolving toward an ideal form
  an idea proposed by Aristotle that suggests that all organisms fit into an orderly scheme
  an idea proposed by Wallace that suggests that organisms change over time
3. Creationism is not accepted as a valid scientific theory because: it violates the scientific principle of natural causality
  it doesn’t offer a model to explain the diversity of life on earth
  it cannot be disproven
  all of these

birds

1. The picture of the finches is used to illustrate: phylogeny of finches
  change over time
  specialization of beaks for different diets
  natural selection
2. Which of the following was not an observation made by Darwin on his voyages: penguins use wings to paddle instead of fly
  snakes have rudimentary hind limbs
  the earth is very old
  islands had species that did not exist on the mainland

bones

1. The image illustrates: vestigial structures
  homologous structures
  the fossil record
  natural selection
2. Which of the following is an example of artificial selection: a panda’s thumb
  the breeding of dogs
  the galapagos finches
  a giraffe’s neck
3. According to the theory of evolution by natural selection, which of the following is true: random mating is necessary for evolution to occur
  variation does not exist between members of the same species
  populations will change to better fit their environment
  individuals will adapt to their environment
4. Which of the following are assumptions made with regards to the Theory of Evolution by Natural selection organisms compete with each other to survive
  variations exist among organisms
  not all organisms that are born survive to reproduce
  all of these

whale

1. The image illustrates which of the following: artificial selection
  acquired characteristics
  homologous structures
  vestigial structures
2. A panda’s thumb is considered an evolutionary contrivance because: it is assembled from wrist bones, and imperfect
  it is perfectly structured to grab leaves
  it is an structure that has no use
  none of these
3. Which of the following outcomes would you predict for a population of bacteria exposed to a new antibiotic. over many generations, the bacteria would become resistant to the antibiotic
  over a few generations, the bacteria would evolve into Archaebacteria
  over a few generations, the bacteria would become extinct
  over many generations, the bacteria would become more susceptible to the antibiotic
4. Which of the following is an example of convergent evolution: whales and sharks have similar body designs
  bees and hummingbirds have similar body designs
  bats and birds have similar body designs
  all of these
5. Why is evolution called the “unifying theory of biology” because it explains the diversity of life on the planet
  because it serves as a model to predict how organisms will change
  it serves as a model to interpret relationships between organisms on the planet
  all of these

moths

The image illustrates how peppered moths are related to other moths
how peppered moths adapted to a changing environment
how peppered moths became extinct
how peppered moths became two species

Ecology

Ecology

All Materials © Cmassengale

Ecology is the study of interactions between organisms (biotic part) and their nonliving environment (abiotic factors)

Biotic factors includes plants, animals, fungi, & microorganisms. They may be producers, consumers, or decomposers.

Abiotic factors include climate, soil, temperature, water, air, sunlight, humidity, pH, and atmospheric gases.

Habitat is the place a plant or animal lives, while its niche is its total way of life.

Life is organized into levels:

Organism (any single living thing)

Population (members of the same species living in one place)

Community (all the populations living in an area)

Ecosystem (community living in a similar habitat such as a forest)

Biomes (ecosystems covering wide areas & with similar climates & organisms)

Biosphere ( all the living & nonliving things on earth)

Producers:

	Make their own food through photosynthesis or chemosynthesis
	Includes plants, algal protists, & some bacteria

Consumers:

	Can’t make their own food
	May be herbivores (feed only on plants), carnivores (feed only on animals), or omnivores (feed on plants & animals)

Decomposers:

	Break down dead plants & animals (detritus)
	Recycle nutrients
	Called detritivores
	Include fungi & bacteria

Sunlight is the ultimate energy for all life on earth, but only producers can get their energy directly from the sun.

Energyflowinecosystemimage

Trophic levels are feeding levels of producers & consumers in an ecosystem:

	1st Trophic Level is producers that use sunlight directly
	2nd Trophic Level includes herbivores that feed directly on plants
	Higher Trophic Levels are carnivores feeding on each other

energypyramid

Food chains & food webs:

	Chains show who eats whom in an ecosystem.
	Webs are made up of several food chains.
	Always begin with producers absorbing sunlight.
	Producers store energy in the chemical bonds of the food they make.
	Stored energy is passed to consumers when they eat producers or other consumers.
	Some energy is lost at each trophic level as heat when consumers “burn” food during cellular respiration.
	Both energy & nutrients must move through an ecosystem.

Three main elements that must move through an ecosystem:

	Water
	Carbon
	Nitrogen

Water or Hydrologic Cycle:

	Cells are 70 – 90% water
	Water is needed for metabolic processes
	Water is most important for terrestrial organisms because of desiccation (drying out)

Steps in the water Cycle:

Evaporation Transpiration
(water loss from lakes, rivers, oceans…) (water loss from plant leaves)

¯ ¯

Condensation
(water vapor forms clouds)

Precipitation
(water returns to earth as sleet, rain, snow…)

Surface Runoff
(returns water to bodies of water or to groundwater)

Carbon Cycle:

	Consists of photosynthesis, cellular respiration, & decomposition
	Begins with producers taking carbon dioxide from the air during photosynthesis
	Carbon dioxide used in cellular respiration
	Decomposing plants and animals return Carbon to the soil

Carbon Cycle Steps:

Plant leaves take carbon dioxide from air

Plants store carbon in carbohydrates or starches
(photosynthesis)

Plants & animals release carbon dioxide back into the air
(cellular respiration)

Decomposers return carbon to environment
(decomposition)

Nitrogen:

	Needed by all organisms
	Used to make proteins & nucleic acids (DNA & RNA)
	Air made up of 80% nitrogen
	Only Cyanobacteria & Rhizobium bacteria can use nitrogen directly from the air (nitrogen fixation)
	Bacteria found in the soil & on the roots of legumes (beans, peas …)

Steps in the Nitrogen Cycle:

Cyanobacteria & Rhizobium take nitrogen from air
(nitrogen fixation)

Convert nitrogen gas into ammonia

Nitrifying bacteria in soil change ammonia into nitrates

Plants can absorb & use nitrates to make proteins

Consumers eat plants & get proteins containing nitrogen

Decomposers break down dead organisms & return nitrogen to air
(called ammonification)

Anaerobic bacteria in soil release nitrogen from nitrates into air
(called denitrification)

Three main types of ecosystems:

	Terrestrial (land)
	Freshwater (rivers, ponds, lakes …)
	Marine (oceans & seas)

Terrestrial ecosystems are divided into 7 biomes with similar climates & organisms

Seven Terrestrial Biomes:

	Tropical Rain Forest (jungle)
	Savanna (tropical grasslands)
	Deserts
	Grasslands
	Deciduous Forest
	Taiga (coniferous forest)
	Tundra

Tundra:

	Cold & dark most of the year
	Includes the arctic
	Permafrost is the top layer of soil that thaws & in which plants grow
	No trees, but sedges & grass, mosses, & lichens
	Many migratory animals
	Lemmings & ptarmigans are year round residents
	Approximately 20 cm annual rainfall

Tundra

Taiga:

Coniferous forest
Extends across northern Eurasia & North America
Contains conifers or evergreens (spruce, cedar, fir, pine …)
Needle like leaves withstand weight of snow
Bear, deer, moose, wolves, mountain lions …
Sequoia or redwood (largest conifer) grows here
Bristle cone pine oldest living conifer found here

Coniferous Forest

Temperate Deciduous Forest:

South of taiga in North America, eastern Asia, & Europe
High annual rainfall (75-150 cm)
Moderate temperatures
Well-defined seasons of about equal length
Trees loose leaves in winter (deciduous)
Show stratification (plant layers):
1. Canopy – broad leaf deciduous trees forming uppermost layer
2. Under story – shrubs
3. Forest Floor – herbaceous plants
Songbirds, deer, rabbits, foxes, squirrels, frogs 7 toads, lizards …

Temperate Deciduous Forest

Tropical Rain forest:

Near equator
Warm climate (20 -25 degrees C)
Plentiful rainfall (190 cm/year)
Contains the greatest diversity of plants & animals
Insects, monkeys & apes, snakes, tropical birds, leopards…
Animals & plants brightly colored
Poor soil for agriculture

Rainforest

Grasslands:

Mostly grasses with a few trees due to less rainfall
Moderate climates
Good for agricultural crops
Grazing & burrowing animals dominate
Also called prairies

Grassland

Savanna:

Tropical grasslands
Warm climate & rainy season
Antelope, zebra, lions, wildebeests, hyenas, elephants…
Suffer from floods & drought

(26KB)

Deserts:

Low annual rainfall
Subject to strong winds
Days usually hot & nights cold
Sahara desert is without vegetation
Succulents such as cacti & other water storing plants
Most animals nocturnal
Lizards, snakes, roadrunners, insects, tarantula, hawks, rodents, coyotes…

Desert

Aquatic Biomes:

May be freshwater or saltwater
Wetlands near oceans have brackish water (mixture of fresh & salt waters)
Part of the part water or hydrologic cycle
Often polluted by man’s activities

Lakes & Rivers:

Freshwater
Oligotrophic lakes are nutrient poor (catfish, carp…)
Eutrophic lake are nutrient rich (trout, bass…)
Deep lakes have layers or strata where different plants & animals live
Phototropic organisms in upper layers for light
Estuary at mouth of river contains brackish water

Ocean Zones:

Intertidal zone
1. Along shoreline
2. Wave action
3. Lots of light so many producers
4. Starfish, sand dollars…
Neritic Zone
1. Ocean water above continental shelf
2. Coral reef found here
3. Surrounds continents & receives light in upper layers
Oceanic Zone
1. Beyond continental shelf
2. Deepest area (up to 7 miles)
3. Bottom doesn’t receive light so animals adapted to darkness (many produce their own light, feed on other animals…)
4. Deepest area called abyss
5. Upper area gets light & called the photic zone (lots of seaweed here)
6. Floaters called plankton (microscopic organisms)
7. Swimmers such as fish called nekton
8. Bottom dwellers called benthos

BACK