# Bio-Process Lab

Bio-Process Lab was a Division B event run in 2008, 2009, and 2010. It returned in 2015 and 2016. The event consists of using various science processes and skills to answer and complete various biological questions and tasks.

Bio-Process Lab was a Division C event from 1984 to 2000, and a Division B event from 1992 to 2000.

## Description

Bio-Process Lab is a lab-oriented competition involving the fundamental science processes of a middle school science program (Div. B) or introductory biology (Div. C). It consists of a series of biological questions or tasks which involve the use of one or more process skills such as formulating and/or evaluating hypotheses and procedures, using scientific instruments to collect data, making observations, presenting and/or interpreting data, or making inferences and conclusions.

That was straight from the rule book. In short, this event is about biology, the scientific method, and knowing how to use equipment like microscopes, etc. It is usually station-based, and often the difficult part is the time constraint rather than the actual material.

Students must bring Z87 chemical splash goggles, and are strongly encouraged to bring a calculator, which must be non-programmable. In addition, each team is allowed to bring one note sheet, front and back.

### Event Concepts

Several concepts are emphasized in Bio-Process Lab, such as

• Ability to interpret nutrition facts on food labels
• Using and making dichotomous keys
• Identifying laboratory equipment and when it is used
• Interpreting pedigree charts
• Parts of a microscope and how to use it
• Population density and ecological analysis
• Converting between and identify metric and customary units
• Distinguishing observations and inferences
• Genetic concepts such as phenotypic and genotypic ratios
• Ability to use indicators such as Benedict's solution, bromothymol blue, and Lugol's Iodine Solution
• Ability to analyze and interpret graphs

## Process Skills

An important aspect of this event is the application of process skills required in a laboratory setting. These processes include observing, inferring, classifying, concluding, predicting, and communicating.

### Observation

Observation is the process of gaining information regarding a certain phenomenon through the use of senses. Because direct observations can only retrieve qualitative data and interpretations of phenomena vary from person to person, measurement is often performed. Measurement is the process of using standard measures or estimations to describe aspects of an object or event. It is capable of giving numerical values to aspects of phenomena, yielding quantitative data.

### Inference

Inference is the process of formulating assumptions or possible explanations based upon observations. It differs from observation in that inferences are not directly perceived, but instead reached with the use of logic and reasoning. For example, one liter of distilled water is poured into a sealable container, along with five grams of table salt, and then the container is sealed and shaken vigorously, after which the grains of table salt are no longer visible; the salt is soluble in water. In this example, the inference is that table salt is soluble in water, which is based on the observation that the grains of salt were no longer visible after the container was shaken.

### Classification

Classification is the process of grouping or ordering objects or events into categories based upon characteristics or defined criteria.

### Communication

Communication is a process by which information is transferred and exchanged. It can be conducted using many different methods, including, but not limited to the use of words, both verbal and written (such as with the event Write It Do It), symbols, and graphics.

### Prediction

Prediction is the guessing of the most likely outcome of a future event based upon a pattern of evidence.

## Optical Microscopes

Main article: Microscope

### Compound Microscopes

The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope (versus an electron microscope). The simplest optical microscope is the magnifying glass and is good to about ten times (10X) magnification. The compound microscope has two systems of lenses for greater magnification, 1) the ocular, or eyepiece lens that one looks into and 2) the objective lens, or the lens closest to the object. Before purchasing or using a microscope, it is important to know the functions of each part.

Eyepiece Lens: the lens at the top that an observer looks through. They are usually 10X or 15X power.

Tube: Connects the eyepiece to the objective lenses

Arm: Supports the tube and connects it to the base

Base: The bottom of the microscope, used for support

Illuminator: A steady light source (110 volts) used in place of a mirror. If a microscope has a mirror, it is used to reflect light from an external light source up through the bottom of the stage.

Stage: The flat platform where an observer places their slides. Stage clips hold the slides in place. If a microscope has a mechanical stage, the slide can be moved by turning two knobs. One moves it left and right, the other moves it up and down.

Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change power.

Objective Lenses: Typically, a microscope has three or four objective lenses. They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X. To have good resolution at 1000X, a relatively sophisticated microscope with an Abbe condenser is required. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are color coded and if built to DIN standards are interchangeable between microscopes. The high power objective lenses are retractable (i.e. 40XR). This means that if they hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide. All quality microscopes have achromatic, parcentered, parfocal lenses.

Rack Stop: This is an adjustment that determines how close the objective lens can get to the slide. It is set at the factory and keeps students from cranking the high power objective lens down into the slide and breaking things. Adjustments to this are typically only required if good focus cannot be attained while using thin slides. If the microscope will not focus on a thin slide, rather than adjust the rack stop a clear glass slide may be placed under the original slide to raise it a bit higher.

Condenser Lens: The purpose of the condenser lens is to focus the light onto the specimen. Condenser lenses are most useful at the highest powers (400X and above). Microscopes with in stage condenser lenses render a sharper image than those with no lens (at 400X). If a microscope has a maximum power of 400X, use a condenser lens rated at 0.65 NA or greater. 0.65 NA condenser lenses may be mounted in the stage and work quite well. A big advantage to a stage mounted lens is that there is one less focusing item to deal with. Going down to 1000X, a focusable condenser lens should be used with an N.A. of 1.25 or greater. Most 1000X microscopes use 1.25 Abbe condenser lens systems. The Abbe condenser lens can be moved up and down. It is set very close to the slide at 1000X and moved further away at the lower powers.

Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide. There is no set rule regarding which setting to use for a particular power. Rather, the setting is a function of the transparency of the specimen, the desired degree of contrast, and the particular objective lens in use.

## Genetics

### Deoxyribonucleic Acid

DNA is a molecule responsible for carrying genetic information. DNA is found in the chromosomes, and is found in the shape of a double helix, which is basically the shape of a twisted ladder. The "rungs" of DNA are made up of adenine, guanine, cytosine, and thymine.

### Genotype

This is the "internally coded, inheritable information" carried by all living organisms. This stored information is used as a "blueprint" or set of instructions for building and maintaining a living creature. These instructions are found within almost all cells (the "internal" part), they are written in a coded language (the genetic code), they are copied at the time of cell division or reproduction and are passed from one generation to the next ("inheritable"). These instructions are intimately involved with all aspects of the life of a cell or an organism. They control everything from the formation of protein macromolecules, to the regulation of metabolism and synthesis.

### Phenotype

Phenotypes are the "outward, physical manifestation" of the organism. They are considered to describe "the physical components" of an organism. These are the physical parts, the sum of the atoms, molecules, macromolecules, cells, structures, metabolism, energy utilization, tissues, organs, reflexes and behaviors; anything that is part of the observable structure, function or behavior of a living organism.

### Karyotypes

Karyotype of a male.

A karyotype is a chart that shows each chromosome. Each karyotype displays 23 pairs of chromosomes, including the X/Y chromosomes. Every pair is assigned a number (except for the sex chromosomes; they are always referred to as the X and Y chromosomes). Some genetic disorders can be detected by analyzing the number of chromosomes and/or the sex chromosomes. The gender of the individual can also be deduced from looking at the sex chromosomes. If there is an X and a Y, the individual is a male. A female has two X chromosomes and no Y chromosome.

A karyotype is created by stopping cells in cell division and staining the chromosomes, then observing them under a light microscope. They can be used to diagnose genetic diseases. For example, a karyotype can reveal a third chromosome 21 (also known as trisomy 21), commonly known as Down Syndrome. It can also reveal Turner syndrome (45, X), a disorder that results in females with one X chromosome, and Klinefelter's syndrome (47, XXY), in which a man has two X chromosomes and one Y chromosome.

### Pedigree charts

A pedigree chart is a chart which tells one all of the known phenotypes for an organism and its ancestors, most commonly humans, show dogs, and race horses. The word pedigree is a corruption of the French "pied de gru" or crane's foot, because the typical lines and split lines (each split leading to different offspring of the one parent line) resemble the thin leg and foot of a crane. Determine if the pedigree chart shows an autosomal or X-linked disease. If most of the males in the pedigree are affected, then the disorder is X-linked. If it is a 50/50 ratio between men and women the disorder is autosomal. Determine whether the disorder is dominant or recessive. If the disorder is dominant, one of the parents must have the disorder. If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous. Autosomal Recessive: Appears in both sexes with equal frequency • Trait tend to skip generations • Affected offspring are usually born to unaffected parents • When both parents are heterozygous, approx. 1/4 of the progeny will be affected • Appears more frequently among the children of consanguineous marriages. DETERMINING GENOTYPES: In the information given, usually in a title, determine if the trait being discussed is dominant or recessive. If the trait is dominant, then individuals with the trait will have their shapes coloured in, if the trait is recessive, then individuals with the trait will have unshaded circles or squares. Locate the recessive individuals in the pedigree, and assign their genotype - two lower case alleles (ff). All of the individuals with the dominant trait will have one capital letter, which expresses the trait. The genotype can be temporarily assigned as capital letter, question mark to represent their alleles (e.g. F?). To determine the second allele, examine the genotypes of the parents or offspring. Each parent must give one allele. If one of the parents is homozygousrecessive, ff, then the offspring must have a heterozygous, Ff, genotype. If both parents are homozygous dominant, FF, then the offspring must also be homozygous dominant, FF.

## Food Webs

Food webs describe the flow of energy within an ecosystem by linking together several food chains. Each food chain begins with an organism that uses energy from light or chemical reactions to produce organic compounds from inorganic compounds through photosynthesis or chemosynthesis, called an autotroph (also referred to as a producer). Any organism that can't produce its own organic compounds and must consume other organisms to obtain them is called a heterotroph (also referred to as a consumer). Heterotrophs can be further organized based on what they consume:

• Herbivore-a heterotroph that only consumes plants
• Carnivore-a heterotroph that only consumes animals
• Omnivore-a heterotroph that consumes both plants and animals
• Detritivore-a heterotroph that consumes detritus (dead and decaying organic matter)
• Decomposer-a heterotroph that breaks down dead and decaying organic matter using biochemical reactions

Note that as opposed to detritivores, decomposers break down dead and decaying organic matter using biochemical reactions without ingesting it.

Each "step" in a food chain is called a trophic level. For example, autotrophs comprise the first trophic level of a certain food chain, the heterotrophs that consume those autotrophs make up the second trophic level, and so on. Within each food chain, only about 10% of the amount of energy that is initially available to one trophic level is available to the organisms in the next trophic level. The other 90% is used to maintain biological processes (e.g., movement, etc.) of the consumed organism, lost as heat, or lost from incomplete digestion.

## Cells

A cell is a collection of biological matter enclosed by a membrane. Cells are the basic unit of all forms of life.

### Cell Theory

Cell Theory is a widely accepted theory which describes properties of cells. It is based on several key points:

• All living things are composed of at least one cell
• Cells are the most basic unit of life
• All cells are produced from pre-existing cells

### Prokaryotic Cells

Main article: Prokaryote

Prokaryotic cells or prokaryotes are cells whose genetic material is not contained within a nucleus and lack membrane-bound organelles. Despite lacking membrane-bound organelles, some prokaryotes contain protein-based microcompartments, which are believed to serve as primordial organelles. Prokaryotes can be split into two domains, bacteria and archaea. Prokaryotes reproduce asexually by means of binary fission.

#### Bacteria

Bacteria are one of two domains of single-celled prokaryotes. Being some of the first known life forms on Earth, bacteria constitute a large chunk of Earth's biomass, and are found in an extremely wide range of environments. Bacteria reproduce asexually by means of binary fission. Some bacteria are autotrophic and obtain their energy by chemosynthesis or photosynthesis, while others are heterotrophic and break down organic matter as a source of energy. While some bacteria are pathogenic and cause disease in organisms, many are mutualistic and carry out extremely important biological processes, such as nitrogen fixation.

#### Archaea

Archaea are one of two domains of single-celled prokaryotes. Archaea share some characteristics with bacteria and eukaryotes, but also have unique characteristics of their own, such as their cell wall structure. Archaea utilize a variety of different energy sources, some undergoing forms of photosynthesis, while others being chemoautotrophic. No archaea have been distinctly identified as directly causing disease, and many are known to be commensalistic or mutualistic. Although many archaea have been identified in seemingly inhospitable environments, such as volcanic hot springs, many also inhabit much more favorable environments, such as oceans, marshes, and even the human body.

### Eukaryotic Cells

Main article: Eukaryote

Eukaryotic cells are cells whose genetic material is contained within a nucleus. In addition, eukaryotic cells also almost always contain membrane-bound organelles, such as mitochondria. Organisms comprised of eukaryotic cells are called eukaryotes. All multicellular organisms are eukaryotes, and some unicellular organisms are eukaryotes. Eukaryotic cells divide either by mitosis or meiosis. Likewise, eukaryotic cells are usually a lot bigger than prokaryotic cells.

### Cytoplasm

Cytoplasm refers the portion of a cell outside the nucleus that's enclosed within the cell membrane. Since prokaryotes don't have a nucleus, all of their contents are considered part of the cytoplasm. The materials composing the cytoplasm can be split into three main categories; organelles, cytosol, and small, insoluble particles called inclusions. Cytosol refers to the area of the cytoplasm not confined within an organelle, and is made of water, organic molecules, and salts. The cytosol also includes the cytoskeleton and other small structures (e.g., ribosomes, etc.). In cell division, the cytoplasm is split between the two daughter cells during cytokinesis.

### Organelles

Organelles are specialized structures within a cell. While most eukaryotic cells contain a multitude of organelles, prokaryotes only sometimes contain protein-based microcompartments.

#### Cell Wall

Structure–a tough layer that surrounds plants, fungi, and prokaryotic cells

Function–protection and support, prevents over-expansion of cell

#### Cell Membrane

Structure–selectively permeable phospholipid bilayer with embedded proteins

Function–protect the cell from its surroundings

#### Nucleus

Structure–double-membrane compartment (referred to as the nuclear envelope), membranes contain pores to regulate transport

Function–DNA maintenance, controls all activities of the cell, RNA transcription

#### Nucleolus

Structure–a round, membraneless body located inside the nucleus of a eukaryotic cell

Function–the site of ribosome synthesis and assembly

#### Endoplasmic Reticulum (ER)

Structure–sheets of unit membrane with ribosomes on the outside and forms a tubular network throughout the cell

Function–transports chemicals between cells and within cell and provides a large surface area for the organization of chemical reactions and synthesis

#### Ribosome

Structure–non-membraneous, spherical bodies composed of RNA (ribonucleic acid) and protein enzymes

Function–the site of protein synthesis

#### Golgi Apparatus

Structure–stacks of flattened sacs of unit membrane (cisternae), vesicles pinch off the edges

Function–modifies chemicals to make them functional, secretes chemicals in tiny vesicles, stores chemicals, may produce endoplasmic reticulum

#### Lysosome

Structure–membrane bound bag containing hydrolytic enzymes

• Hydrolytic Enzyme-water split biological catalyst i.e. using water to split chemical bonds

Function–break large molecules into small molecules by inserting a molecule of water into the chemical bond

#### Mitochondrion

Structure–composed of modified double unit membrane (protein, lipid), inner membrane infolded to form cristae

Function–site of cellular respiration ie. the release of chemical energy from food

Glucose + Oxygen -----> Carbon Dioxide + Water + Energy (ATP)

#### Chloroplast

Structure–composed of a double layer of modified membrane (protein, chlorophyll, lipid), inner membrane invaginates to form layers called "grana" (sing., granum) where chlorophyll is concentrated

Function–site of photosynthesis

Light + Carbon Dioxide + Water -----> Glucose + Oxygen

### Cell Division

Cell division is a part of the cell cycle in which a parent cell's growth stops and it separates into two or more daughter cells. In prokaryotes, it occurs through the process of binary fission, in which the cell nearly doubles in size, replicates its DNA, and divides in half. Although binary fission does not involve the exchange or recombination of genetic information, many bacteria exchange genetic information through a process called conjugation. In eukaryotes, cell division occurs through both mitosis and meiosis, described in more detail below.

#### Mitosis

Mitosis is a form of cell division in which after a parent cell replicates its genetic information, the parent cell splits to form two identical daughter cells. Because the two daughters are genetically identical to the parent cell, mitosis is essential for growth, development, and the replacement of cells in multicellular organisms. Additionally, asexually reproducing eukaryotes reproduce through mitosis (e.g., if an organism reproduces through asexual budding, the cells that comprise the mass that will become the new organism reproduce through mitosis). The process of mitosis can be defined in several distinct phases:

• Prophase-Chromatin condenses into chromosomes and the spindle apparatus is synthesized. In animal cells, centrosomes (a pair of centrioles surrounded by proteins) organize the spindle apparatus, while in plant cells the nuclear envelope serves as the primary organizer of the spindle apparatus.
• Prometaphase-Nuclear envelope disintegrates and spindle apparatus attaches to the chromosomes.
• Note that prometaphase is not always recognized, sometimes being included as part of prophase. It is also sometimes referred to by a different term, such as late prophase.
• Metaphase-Chromosomes align in the center between the centrosomes.
• Anaphase-The chromosomes separate and move towards the centrosomes.
• Telophase-The chromosomes loosen into chromatin as the nuclear envelopes of the daughter cells start to form. Cytokinesis starts to begin.

In the final stage of cell division, known as cytokinesis, the cytoplasm of the parent cell is divided between the daughter cells as it splits to become the two new daughter cells. Once this separation occurs, the process of cell division is complete.

#### Meiosis

Meiosis is a form of cell division in which after a parent replicates its genetic information, it splits to form two daughter cells, and those daughter cells split once more without replicating its genetic information, resulting in four cells with only half the number of chromosomes as the original parent cell. Those cells produced through meiosis are referred to as haploid cells, as they contain a single set of chromosomes, as opposed to cells which contain two pairs of chromosomes, which are known as diploid cells. For example, most human cells are diploid and contain 23 pairs of chromosomes, or 46 total, while sperm and egg cells contain only one pair of 23 chromosomes and are therefore haploid cells.

The process by which the original parent cell and its daughter cells divide in meiosis are the same as in mitosis, going through prophase, prometaphase, metaphase, anaphase, and telophase in respective order. Note that during meiosis when the original parent cell divides, each phase is referred to as (name of stage) I, such as prophase I, prometaphase I, and so forth, and when the daughter cells of the original parent cell split into 4 haploid cells, each phase is referred to as (name of stage) II, such as prophase II, prometaphase II, and so forth.

## Acids, Bases, and Indicators

Acid: A substance that contains an abundance of hydrogen ions. Acids are known to be sour (it's best not to taste them!), abrasive, and can turn litmus paper red.

Base: A substance that contains an abundance of hydroxide ions. Bases are known to taste bitter, feel soapy and slippery, and can turn litmus paper blue.

Neutralization: When an acid and base are put together, they form a salt and water.

pH Scale: A scale that goes from 0 through 14, and is used to determine the concentration of hydrogen or hydroxide ions. The lower the number, the more acidic. The higher the number, the more basic. If the number is 7, it is neutral.

Iodine tests for starch

## Measurement Devices

In Bio-Process Lab, competitors are expected to be able to use many different common measurement devices. Some examples of measurement devices competitors might be asked to use are highlighted in the table below.

Measurement Devices
Measurement Device Description
Calipers Used to measure the widths of objects
Double Pan Balance Compares the mass of two objects; can be used to measure an object's mass by using predetermined masses
Graduated Cylinder Used to measure volumes of liquids; can also be used to measure volumes of solids by placing the solid in a predetermined amount of liquid and observing how much liquid is displaced by the solid
Litmus Paper Strips of paper treated with litmus used as an indicator of pH
Ruler Used to measure length
Thermometer Used to measure temperature
Triple Beam Balance Used to measure the mass of an object

## Reference

### Terms To Know

Term Definition
Alleles Different variations of the same gene
Archaea One of two domains of prokaryotes; share some characteristics with bacteria and eukaryotes, but also have unique characteristics of their own, (e.g., their cell wall structure)
Arm The part of a compound microscope that connects the tube to the base
Asexual Reproduction Reproduction that does not involve the union of gametes; results in offspring that are genetically identical to their parent
Bacteria One of two domains of prokaryotes; live in an extremely wide range of environments; some bacteria cause disease while many are mutualistic and carry out extremely important biological processes
Binary Fission The asexual process by which prokaryotes reproduce; the DNA is reproduced, the original DNA and replicated DNA move to opposite sides of the cell, and a cell wall forms to separate the two, forming the daughter cells
Cell A collection of biological matter; the basic unit of all life
Cell Cycle The series of events that take place in a cell as it grows, develops, and reproduce
Cell Division A part of the cell cycle in which a parent cell's growth stops and it separates into two or more daughter cells
Cell Membrane A selectively permeable phospholipid bilayer with embedded proteins that protect the cell from its surroundings
Cell Theory A widely accepted theory which describes properties of cell, primarily that all living things are composed of at least one cell, cells are the most basic unit of life, and all cells are produced from pre-existing cells
Cell Wall A tough layer that surrounds plants, fungi, and prokaryotic cells; provides protection and support for cell and prevents over-expansion
Co-dominance Both dominant alleles in an individual are expressed and visible in the phenotype
Conjugation The transfer of genetic material between bacterial cells by direct contact or by a bridge-like connection between two cells
Cytoplasm The portion of a cell that's enclosed within the cell membrane excluding the contents of the nucleus; comprised of organelles, cytosol, and small, insoluble particles called inclusions
Cytosol The area of the cytoplasm not confined within an organelle; made of water, organic molecules, and salts
Daughter Cell The cells produced through cell division
Diaphragm A rotating disk under the stage used to vary the amount of light passing through the stage opening
Dominant Allele An allele that will always be expressed, except for occurrences such as, but not limited to, co-dominance
Eukaryotic Cell A cell whose genetic material is contained within a nucleus; contain membrane-bound organelles
Eyepiece Lens The lens at the top of a compound microscope that an observer looks into
Genotype The genetic makeup of an organism or group of organisms with reference to certain traits
Golgi Apparatus Stacks of flattened sacs of unit membrane (cisternae), vesicles pinch off the edges; it modifies chemicals to make them functional, secretes chemicals in tiny vesicles, stores chemicals
Illuminator A steady light source commonly used in place of a mirror in compound microscopes
Karyotype A photograph of chromosomes grouped in order in pairs
Lysosome Membrane bound bag containing hydrolytic enzymes that break large molecules down into small molecules by inserting a molecule of water into the chemical bond
Monosomy A genetic discrepancy in which an individual is missing a chromosome
Multicellular Consisting of multiple cells
Multiple Alleles A type of non-Mendelian inheritance pattern where there are three or more alleles for a single trait; results in three or more phenotypes (e.g., blood types)
Nondisjunction The failure of chromosomes to completely separate and segregate into daughter cells during meiosis; results in monosomy or trisomy
Nuclear Envelope The double-membrane that encloses a cell nucleus
Nucleolus A round, membraneless body located inside the nucleus of a eukaryotic cell; the site of ribosome synthesis and assembly
Nucleus Double-membrane compartment, membranes contain pores to regulate transport; the location of DNA maintenance and RNA transcription; controls all activities of the cell
Objective Lens The lens of a compound microscope closest to the object; common powers are 4x, 10x, 40x, and 100x
Organelle Specialized structures within a cell
Parent Cell The cell that splits to form daughter cells in cell division
Pedigree A chart which displays all of the known phenotypes for an organism and its ancestors
Phenotype The physical appearance of an organism resulting from the interaction of the genotype and the environment
Prokaryotic Cell A cell whose genetic material is not contained within a nucleus and lack membrane-bound organelles
Punnett Square A genetic probability diagram used to show the gametes of each parent and their possible offspring
Rack Stop An adjustment of compound microscopes that determines how close the objective lens can get to the slide
Recessive Allele An allele that can be masked by any present dominant alleles
Revolving Nosepiece Also known as a turret, the part of a compound microscope that holds two or more objective lenses and can be rotated to easily change power
Ribosome Non-membraneous, spherical bodies composed of RNA (ribonucleic acid) and protein enzymes; the site of protein synthesis
Sexual Reproduction Reproduction involving the union of gametes; results in genetic variation among offspring
Stage The flat platform on compound microscopes where one places their slides for observation
Stage Clips Clips on a compound microscope's stage used to hold the slide in place
Trisomy A genetic discrepancy in which an individual has an extra chromosome
Tube Connects the eyepiece to the objective lenses in a compound microscope
Turret Also known as a revolving nosepiece, the part of a compound microscope that holds two or more objective lenses and can be rotated to easily change power
Unicellular Consisting of one cell

### Metric Scale

Competitors in this event should be familiar with the metric scale. Although the table below displays all metric prefixes, the prefixes above giga- and below nano- are rarely used.

#### Metric Prefixes

Metric Prefixes
Prefix Symbol Multiplier
yotta Y $10^{24}$
zetta Z $10^{21}$
exa E $10^{18}$
peta P $10^{15}$
tera T $10^{12}$
giga G $10^9$
mega M $10^6$
kilo k $10^3$
hecto h $10^2$
deca (also deka) da $10^1$
--- --- $10^0$
deci d $10^{-1}$
centi c $10^{-2}$
milli m $10^{-3}$
micro $\mu$ $10^{-6}$
nano n $10^{-9}$
pico p $10^{-12}$
femto f $10^{-15}$
atto a $10^{-18}$
zepto z $10^{-21}$
yocto y $10^{-24}$

#### Other Units

• A metric ton or tonne is 1,000 kilograms, or 1 megagram
• Kelvin is degrees Celsius plus 273.15