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Kenneth Kang

Monday, November 20, 1995

Biology

Chapter 20: Organizing Life

Classification

An extension to classification is biodiversity (X-Ref Discover November 1995 tree article).

How Classification Began

"CLASSIFICATION is the grouping of objects or information based on similarities." It is done to better understand life and find what to eat. TAXONOMY is the specific branch that groups and names organisms.

Aristotle (384-322 B.C.) classified things by where they were found. Linaeus (1707-1778) classified by how closely things were related to each other. He named them by GENUS which is the family of related species and by another word. His system is called the BINOMIAL NOMENCLATURE. We use his system in the following convention: capitalized genus name followed by a lower case species name all underlined. (e.g. Homo sapiens, Canis lupus commonly known as a worf, Canis familiarus commonly known as a dog)

TaxonomyThe Study of Classification

The study of classification tries to place things so that they are related or different to each organism. It can identify certain species to aid whoever wishes to know. (A kid eats a unknown mushroom! Russian roulette! Taxo-man to the rescue!) Discoveries of new plants that cure stuff are found by taxonomists. Classification is dynamic and changes as taxonomist meet every 10 years and publish information

How Living Things Are Classified

They are put in to more and more specific categories. FAMILY is the group immediately larger than the genus. The remaining hierarchy from smallest to largest is as follows: ORDER, CLASS, PHYLUM, and KINGDOM. The complete hierarchy from smallest to largest is as follows: species, genus, family, order, class, phylum, and kingdom. The species is determined by a group of organisms that can mate and produce fertile young. The separation between animal and plant kingdoms is called DIVISIONS. This method that we will be using is called phylogenetic classification which categorizes stuff by its characteristics and similar ancestors. (An example would be a elephant's closes living relative is a much smaller hyrax.)

Fossils, Anatomy, and Embrylogy are used to classify things. Fossils, the mineralized remains of a hard part of an organism, can be similar in length, width, thickness, holes, and rough areas. The holes and rough areas are landmarks which are used to guess what functions the stuff had. Embriology determines the "origin" of each structure. Homologous structures are the ones that originate from the same embrionic stuff and grow into the same thing. A bat's wing is homologous to your hand. Analogous structures are structures that look and function alike but do not originate from the same embrionic thing.

There are five major kingdoms. The first of them appeared 3.75 109 years ago. The kingdoms are plant, animal, monerans (prokaryotes, mainly bacteria), protista (eukaryotic single-celled), and fungi (e.g. mushrooms has chitin and decomposes stuff).

How Are Relationships Determined?

Classification is determined by structure, behavior, and chemistry. Evolutionary history also plays a role. Because of similarities in the three characteristics above, scientist conclude that the animals share the same ancestor. Fossils also help determine a species's PHYLOGENY or evolutionary history. This type of classification lets scientists infer other characteristics from one specimen about other specimens. Sometimes scientists will classify animals together because they develop (grow) in a similar way. DNA comparisons can reveal the "closeness" of two species. Behavior can show that one species does something differently than another.

Scientific Names

To prevent confusion, taxonomists use Latin and the binomial nomenclature instead of the common names. They are underlined or italicized with the first letter of the entire name capitalized.

Review Questions

  1. Using the optimum dichotomy chart, what is the fewest number of comparisons necessary to uniquely identify 2048 organisms?
  2. Imagine two animals, without research, how would you classify them? What do scientists say? Why?

The Five Kingdoms

Phylogenetic Classification: A Model

This model arose after the study of geologic time. As you continue learning refer to the picture in the back cover or on page 492-493 which shows all the kingdoms emanating from a single point in time.

How the Five Kingdoms are Distinguished

The major differences are cellular and the acquisition of food. The MONERANS are the ones without the nuclei in membranes. These live everywhere and originated 3.5 billion years ago. Ten thousand species have been identified. These are the only prokaryotic kingdom.

The PROTISTAS are eukaryotic and sans organs. Fossilized up to 1 billion years ago, 90,000-200,000 species have been identified.

The FUNGUS kingdom is both uni- and multi-cellular and munches on dead organisms. Fossilized up to 400 million years ago, 100,000 plus species have been identified. They are multi-cellular and are saprophytes which means they suck up liquid nuitrition from decaying matter. They have cell walls of chitin.

The plantae kingdom photosynthesize stuff and have organs! They have been fossilized since 400 million years ago and 500,000 species have been identified. The have cellulose cell walls and most photosynthesize.

The kingdom animalia get food from other organisms. Fossils show animals up to 700 million years old. These creatures are mobile!

Review Questions

  1. Imagine a new kingdom. What characteristics does it have? Why do you need a new kingdom?
  2. What type of organism (real or imaginary) would fall under two kingdoms? How would you place the organism? Why?

Chapter 26: Flowering Plants

What Is an Angiosperm

Diversity of Angiosperms

Plants that have flowers and seeds within fruit are ANGIOSPERMS. They are classified in division Anthophyta under two classes. They are MONOCOTYLDONS and DICOTYLEDONS which are plants that have one and two seed leaves respectively. Examples of dicots like the peanut have seeds that can split. Dicotyledons comprise more of the flowering species than the moncotyldons.

Angiosperm Adaptations

They are a well evolved group found almost everywhere. They have bulbs, which are leafy stems; corms, which are underground stems without the leafyness; and tubers, which are fat roots or stems that make new plants; for storing food.

ANNUALS are anthophytes that die after one year. Similarly, BIENNIALS live during one year and reproduce and die the next. PERENNIALS life, "for several years...."

Review Questions

  1. Names some common anthophytes. How are they adapted to their environment?
  2. Using SimLife, design your own plant. What adaptations does it have? How long did it live?

Angiosperm Structures and Functions

Roots

The roots have 50%+ TSA than leaves. The EPIDERMIS is the outer layer. The ROOT HAIR is "a single epidermal cell that increases the surface area of the root...." The CORTEX transports the water and junk to the vascular things. The PARENCHYMA sometimes stores food and water and occurs throughout the plant. The ENDODERMIS controls the flow of water and waterproofs the thing. The PERICYCLE makes "lateral roots." The xylem and phloem are the innermost things and the CAMBIUM produces more of them.

The APICAL MERISTEM grows and mitosisizes. It makes the protective ROOT CAP.

Digressing a little, any MERISTEM is a growing area of a plant. The root meristem or APICAL MERISTEM is the tip of the root that grows. The cells it leave behinds specialize. Some genes turn on or off making the cell different. The EPIDERMIS is the protective covering. The VASCULAR TISSUES are the ones that tranport stuff. These specialize into the PRIMARY XYLEM, the water transporter from the root to the plant,. and PRIMARY PHLOEM, the food trasport from the rest of the plant to the root. The ENDODERM is the thing that prevents the vascular tissue from leaking. The PERICYCLE is the thing that branch roots will grow from. The CORTEX is the thing that provides starch storage. The picture on 642 shows a monocot root structure.

Functions in Brief

Review Questions

  1. What is the difference between a monocot and dicot root structure?
  2. Look at the stem structure. What similarities and differences do you notice?

Stems

There are two types. The herbaceous stem grows and dies every year while the woody stems just remain for years. A lot like the roots, the stems between the dicots and monocots vary and they also have different placements than the roots.

The woody ones grow wider every year. This is known as secondary growth. The BARK protects the vascualr tissues. The SINK is the general terms for any part that stores food. The vascual tissues are made of VESSEL CELLS which have open tops and bottoms. Phloem has SIEVE CELLS which needs a COMPANION CELL which controls it when it transports sugars.

The trunk (X-Ref Text 643) has four functional layers on the outside. The outer most is the phloem. The second level is the VASCULAR CAMBIUM which produces a new layer of xylem and phloem every year. The two innermost functional layers is the xylem.

Review Questions

  1. Explain how tree rings are made.
  2. As the vascular cambium makes more phloem and xylem tissue, where do the older tissues go?

Water Transport

This is purely theoretical and is being debated. The Xylem transports water and dissolved minerals to the leaves from the roots. The first step from the ground to the roots is done by osmosis through the root hairs. The second step is harder. The stem must work against friction and gravity to raise the water up. The Xylem cells have evolved to have sieves in long tubes. These tube cells have no nuclei so they eventually die and get filled with gum to form heartwood.

One of the methods is called Transpiration-Cohesion. This is where the leaves lose water and the cohesion between the water molecules pulls the water up from the ground. Cohesion is the attration from like molecules.

Review Questions

  1. What are some arguements against this hypothesis?
  2. How could you test this hypothesis?

Leaves

This has already been studied to a degree.

The part to the leaf itself is the PERTIOLE. The leaves lose water through TRANSPIRATION. GUARD CELLS minimize this loss of water. The two layers of MESOPHYLL do the photosynthesis.

Review Questions

  1. Hypothesize on the factors of water loss. Try to find an appropriate mathematical model.
  2. Why is there less surface area on the leaves than on the roots?

Parts of a Flower

(X-Ref text P. 658)

Part              Description                                                    

Sepals            the bud leaves                                                 
                  provide protection for the bud                                 

Anther            produces the pollen                                            
                  the male part of the plant                                     

Filament          holds the anther                                               

Pistil            the female part of the plant                                   

Stigma            the sticky part that is supposed to get pollen                 

Ovary             produces the egg cell                                          
                  the place of fertalization                                     
                  the fruit in fruit plants (aids is the spread of seeds cause   
                  animals eat)                                                   

Style             the thing that holds the stigma                                

Petal             supports and attracts the pollinator                           

Ovule             "the egg"                                                      


Table 1: Parts of a Flower

Reveiw Questions

  1. What do the petals do?
  2. What would be a creative way to pollenate a flower? (For the courageous, name a way that nature hasn't found.)


Page created by Kenneth Kang on 1/4/97