Category: Curriculum Map

Fungi

 

Fungi
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Characteristics

  • Eukaryotic 
  • Do not contain chlorophyll
  • Nonphotosynthetic
  • Absorptive heterotrophs – digest food first & then absorb it into their bodies
  • Release digestive enzymes to break down organic material or their host
  • Store food energy as glycogen
  • Most are saprobes – live on other dead organisms
  • Important decomposers & recyclers of nutrients in the environment
  • Most are multicellular, but some unicellular like yeast
  • Some are internal or external parasites; a few are predators that capture prey
  • Nonmotile
  • Lack true roots, stems, & leaves
  • Cell walls are made of chitin (a complex polysaccharide)
  • Grow as microscopic tubes or filaments called hyphae that contain cytoplasm & nuclei
  • Hyphal networks are called mycelium
  • Some are edible
  • Reproduce by sexual & asexual spores
  • Antibiotic penicillin comes from Penicillium mold
  • Classified by their sexual reproductive structures
  • Grow best in warm, moist environments preferring shade
  • Mycology – study of fungi
  • Fungicide – chemicals used to kill fungi
  • Includes yeasts, molds, mushrooms, ringworm, puffballs, rusts, smuts, etc.
  • Fungi may have evolved from prokaryotes by endosymbiosis

Vegetative (nonreproductive) Structures of Fungi

  • Body of a fungus made of tiny filaments or tubes called hyphae
  • Hyphae contain cytoplasm & nuclei and has a cell wall of chitin


HYPHAE

  • Each hyphae is one continuous cell
  •  Hyphae continually grow & branch
  • Septum (septa-plural) are cross walls with pores to allow the movement of cytoplasm in hyphae
  • Hyphae with septa are called septate hyphae
  • Hyphae without septa are called coenocytic hyphae

  • Tangled mats of hyphae are known as mycelium
  • All hyphae within a mycelium share the same cytoplasm so materials move quickly
  • Hyphae grow rapidly from the tips by cell division
  • Stolon is a horizontal hyphae that connects groups of hyphae to each other
  • Rhizoids are rootlike parts of hyphae that anchor the fungus

Reproductive Structures

  • Most fungi reproduce asexually & sexually
  • Asexual reproduction produces genetically identical organisms & is the most common method used
  •  Sexual reproduction in fungi occurs when nutrients or water are scarce
  • Fruiting bodies are modified hyphae that make asexual spores
  • Fruiting bodies consist of an upright stalk or sporangiophore with a sac containing spores called the sporangium


SPORANGIOPHORES

  • Types of fruiting bodies include basidia, sporangia, & ascus
  • Spores – haploid cells with dehydrated cytoplasm & a protective coat capable of developing into new individuals
  • Wind, animals, water, & insects spread spores
  • When spore lands on moist surface, new hyphae form

Asexual Reproduction in Fungi

  • Fungi reproduce asexually when environmental conditions are favorable
  • Some unicellular fungi reproduce by mitosis
  • Yeast cells reproduce by budding where a part of the cell pinches off to produce more yeast cells

  • Athlete’s foot fungus reproduce by fragmentation from a small piece of mycelium
  • Most fungi reproduce asexually by spores
  • Penicillium mold produces spores called conidia without a protective sac on the top of a stalk called the conidiophore

Sexual Reproduction in Fungi

  • Fungi reproduce sexually when environmental conditions are unfavorable
  • No male or female fungi
  •  Two mating types — plus (+) and minus (-)
  • Fertilization occurs when (+) hyphae fuse with (-) hyphae to form a 2N or diploid zygote
  • Some fungi show dimorphism (ability to change their form in response to their environmental conditions)

Classification of Fungi

  • Fungi are classified by their reproductive structures
  • The 4 phyla of fungi are Basidiomycota, Zygomycota, Ascomycota, & Deuteromycota

Zygomycota

  • Called sporangium fungi or common molds
  • Includes molds & blights such as Rhizopus stolonifer (bread mold)

  • No septa in hyphae (coenocytic)
  • Asexual reproductive structure called sporangium & produces sporangiospores
  • Rhizoids anchor the mold, release digestive enzymes, & absorb food
  • Asexual reproductive structure called sporangium & produces sporangiospores
  • Sexual spore produced by conjugation when (+) hyphae & (-) fuse is called zygospore
  • Zygospores can endure harsh environments until conditions improve & new sporangium

 

 

Basidiomycota

  • Called club fungi
  •  Includes mushrooms, toadstools, puffballs, bracket fungi, shelf fungi, stinkhorns, rusts, & smuts
  • Some are used as food (mushroom) & others cause crop damage (rusts & smuts)
  • Seldom reproduce asexually
  • Basdiocarp made up of stalk called the stipe & a flattened cap
  • Stipe may have a skirt like ring below cap called the annulus
  • Gills are found on the underside of the cap & are lined with basidia
  • Basidium – sexual reproductive structure that make basidiospores
  • Basidiospores are released from the gills & germinate to form new hyphae & mycelia
  • Vegetative structures found below ground & include rhizoids (anchor & absorb nutrients), hyphae, & mycelia

Ascomycota

  • Called sac fungi
  • Includes yeast, cup fungi, truffles, powdery mildew, & morels

  • Some are parasites causing Dutch elm disease & chestnut blight
  • Sac Fungi can reproduce both sexually and asexually
  •  Yeast reproduce asexually by budding (form small, bud-like cells that break off & make more yeasts)
  • Asexual spores called conidia form on the tips of specialized hyphae called condiophores
  • Ascocarp – specialized hyphae formed by parent fungi during sexual reproduction
  • Ascus – sacs within the ascocarp that form spores called ascospores

Lichens

  • Symbiotic association between a sac fungus & a photosynthetic green algae or cyanobacteria
  • Both organisms benefit (algae makes food & fungus supplies moisture, shelter, & anchorage)
  • Grow on rocks, trees, buildings, etc. & help form soil
  • Crustose lichens grow on rocks & trees; fructose lichens grow shrub-like; foliose lichens grow mat-like on the soil

Mycorrhizae

  • Symbiotic association of a fungus living on plant roots
  • Most plants have mycorrhizae on their roots
  • Fungus absorbs sugars made by plant
  • Plants absorb more water & minerals with aid of the fungus

Importance of Fungi

  • Fungal spores cause allergies
  • Molds, mildew, rusts, & smuts damage crops
  • Yeasts are used to make beer & bread
  •  Antibiotic penicillin
  • Decomposers & recyclers of nutrients
  • Mushrooms eaten as food
  • Help form blue cheeses
  • Aspergillus is used to make soy sauce
  • Cause athlete’s foot & ringworm
  • Amanita is poisonous mushroom
  • Can cause yeast infections

 

Pig Heart Dissection

 

Heart Dissection

Introduction
Mammals have four-chambered hearts and double circulation. The heart of a bird or mammal has two atria and two completely separated ventricles. The double-loop circulation is similar to amphibians and reptiles, but the oxygen-rich blood is completely separated from oxygen-poor blood. The left side of the heart handles only oxygenated blood, and the right side receives and pumps only deoxygenated blood. With no mixing of the two kinds of blood, and with a double circulation that restores pressure after blood has passed through the lung capillaries, delivery of oxygen to all parts of the body for cellular respiration is enhanced. As endotherms, which use heat released from metabolism to warm the body, mammals require more oxygen per gram of body weight than other vertebrates of equal size. Birds and mammals descended from different reptilian ancestors, and their four-chambered hearts evolved independently – an example of convergent evolution.

Objective
Using a pig heart, students will observe the major chambers, valves, and vessels of the heart and be able to describe the circulation of blood through the heart to the lungs and back and out to the rest of the body. (The pig heart is used because it is very similar to the human heart in structure, size, & function.)

Materials
Dissecting pan, dissecting kit, safety glasses, lab apron, pig heart, & gloves

Procedure – External Structure

  1. Place a heart in a dissecting pan & rinse off the excess preservative with tap water. Pat the heart dry.
  2. Examine the heart and locate the thin membrane or pericardium that still covers the heart. The pericardium or pericardial sac, is a double-layered closed sac that surrounds the heart and anchors it.  The pericardium consists of two tissues layers – the visceral pericardium that covers the surface of the heart & the parietal pericardium covering the inner surface of the parietal sac. These two tissue layers are continuous with each other where the vessels enter or leave the heart. The slender gap between the parietal & visceral surfaces is the pericardial cavity & is filled with fluid to reduce friction between the layers as the heart pumps.
  3. After examining the pericardium, carefully remove this tissue. Located below the pericardium is the muscle of your heart called the myocardium. Most of the myocardium is located in the lower two chambers of the heart called ventricles.
  4. Locate the tip of the heart or the apex. Only the left ventricle extends all the way to the apex.
  5. Place the heart in the dissecting pan so that the front or ventral side is towards you ( the major blood vessels are on the top and the apex is down). The front of the heart is recognized by a groove that extends from the right side of the broad end of the heart diagonally to a point above & to your left of the apex.


Front or Ventral Side of the Heart

  1. The heart is now in the pan in the position it would be in a body as you face the body. Locate the following chambers of the heart from this surface:
    • Left atria – upper chamber to your right
    • Left ventricle – lower chamber to your right
    • Right atria – upper chamber to your left
    • Right ventricle – lower chamber to your left

pig heart dissection

  1. While the heart is still in this position in the dissecting pan, locate these blood vessels at the broad end of the heart:
  • Coronary artery – this blood vessel lies in the groove on the front of the heart & it branches over the front & the back side of the heart to supply fresh blood with oxygen & nutrients to the heart muscle itself.
  • Pulmonary artery – this blood vessel branches & carries blood to the lungs to receive oxygen & can be found curving out of the right ventricle (upper chamber to your left)
  • Aorta – major vessel located near the right atria & just behind the pulmonary arteries to the lungs. Locate the curved part of this vessel known as the aortic arch. Branching from the aortic arch is a large artery that supplies blood to the upper body.
  • Pulmonary veins – these vessels return oxygenated blood from the right & left lungs to the left atrium (upper chamber on your right)
  • Inferior & Superior Vena Cava – these two blood vessels are located on your left of the heart and connect to the right atrium (upper chamber on your left).  Deoxygenated blood enters the body through these vessels into the right receiving chamber.  Use your probe to feel down into the right atrium. These vessels do not contain valves to control blood flow.

 

Procedure – Internal Anatomy:

  1. Use scissors to cut through the side of the pulmonary artery and continue cutting down into the wall of the right ventricle. Be careful to just cut deep enough to go through the wall of the heart chamber. (Your cutting line should be above & parallel to the groove of the coronary artery.)
  2. With your fingers, push open the heart at the cut to examine the internal structure. If there is dried blood inside the chambers, rinse out the heart.
  3. Locate the right atrium. Notice the thinner muscular wall of this receiving chamber.
  4.  Find where the inferior & superior vena cava enter this chamber & notice the lack of valves.
  5. Locate the valve that between the right atrium and right ventricle. This is called the tricuspid valve. The valve consists of three leaflets & has long fibers of connective tissue called chordae tendinae that attach it to papillary muscles of the heart. This valve allows blood flow from the right atrium into the right ventricle during diastole (period when the heart is relaxed). When the heart begins to contract (systole phase), ventricular pressure increases until it is greater than the pressure in the atrium causing the tricuspid to snap closed.


Tricuspid Valve

  1. Use your fingers to feel the thickness of the right ventricle and its smooth lining. Also note the network of irregular muscular cords on the inner wall of this chamber.
  2. Find the septum on the right side of the right ventricle. This thick muscular wall separates the right & left pumping ventricles from each other.
  3. Inside the right ventricle, locate the pulmonary artery that carries blood away from this chamber. Find the one-way valve called the pulmonary valve that controls blood flow away from the right ventricle at the entrance to this blood vessel.
  4. Using your scissors, continue to cut open the heart.  Start a cut on the outside of the left atrium downward into the left ventricle cutting toward the apex to the septum at the center groove. Push open the heart at this cut with your fingers & rinse out any dried blood with water.
  5. Examine the left atrium. Find the openings of the pulmonary veins form the lungs. Observe the one-way, semi-lunar valves at the entrance to these veins.
  6. Inside this chamber, look for the valve that controls blood flow between the upper left atrium and lower left ventricle. This valve is called the bicuspid or mitral valve. This valve consists of two leaflets & blood flows from the left atrium into the left ventricle during diastole.

 

The mitral valve
Bicuspid or Mitral Valve

  1. Examine the left ventricle. Notice the thickness of the ventricular wall. This heart chamber is responsible for pumping blood throughout the body.
  2. Using your scissors, cut across the left ventricle toward the aorta & continue cutting to expose the valve.
  3. Count the three flaps or leaflets on this valve leading from the left ventricle into the aorta and note their half-moon shape. This is called the aortic valve.
  4. Using scissors, cut through the aorta and examine the inside. Find the hole or coronary sinus in the wall of this major artery. This leads into the coronary artery which carries blood to and nourishes the heart muscle itself.
  5. Answer the questions on your lab report.

Click here for questions

When you have finished dissecting the heart, dispose of the heart as your teacher advises and clean, dry, and return all dissecting equipment to the lab cart. Wash your hands thoroughly with soap.

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Fungi Study Guide B1

Fungi Study Guide

 

Know the following:

 

  • general characteristics of all fungi
  • how fungi get their nutrients
  • what makes up the cell walls of fungi
  • are fungi heterotrophic or autotrophic & why
  • can fungi carry on photosynthesis
  • how fungi growing on the roots of plants help them
  • what causes ringworm
  • what are sporangia
  • know the parts of a mushroom & which parts acquire food for the organism
  • how fungi obtain their energy
  • where fungi digest their organic matter
  • what is a hyphae
  • What mats of hypha are called
  • steps in the life cycle of a mold
  • what part of a mold releases enzymes & absorbs digested food
  • what must happen for sexual reproduction to occur between mold hypha
  • examples of club fungi
  • phylum for mushrooms
  • characteristics of sac fungi or ascomycetes
  • what type of spores allow molds to remain dormant during harsh conditions
  • most common member of the zygomycete group
  • what are sporangia & what forms inside them
  • what is an example of a unicellular fungus
  • how do yeasts asexually reproduce
  • what 2 things make up the body of a lichen
  • why are fungi so important to the environment

Genetics Study Guide BI

Genetics Study Guide 

The two genes or alleles that combine to determine a trait would be the organism’s _______________.
Type AB blood, having two genes dominant for a trait, is an example of ________.
State Mendel’s law of segregation.
Rr x Rr is an example of what type of cross —– P1, F1, or F2?
If both alleles are the same in a genotype, is the genotype homozygous or heterozygous?
Which cross is a cross between two hybrids —– P1, F1, or F2?
__________ dominance results in the blending of genes in the hybrid. Give an example using flower color.
What is another term for a heterozygous genotype?
The _____________ is the physical feature such as round peas that results from a genotype.
How many traits are involved in a monohybrid cross?
What type of organism was used in the first genetic studies done by Gregor Mendel?
What is a karyotype?
The two genes for a trait represented by capital & lower case letters are called __________.
How many traits are involved in a dihybrid cross?
Which of Mendel’s laws states that the dominant gene in a pair will be expressed?
If both alleles are the same, is the genotype homozygous or heterozygous? Write an example.
Write an example of a hybrid or heterozygous genotype.
The genes for sex-linked traits are only carried on which chromosome?
Who is considered to be the “father of genetics”?
A second filial or F2 cross is also called a ____________ cross.
The failure of chromosomes to separate during meiosis (egg & sperm formation) is known as _________________.
A cross between two pure or homozygous organisms is called what type of cross —– P1, F1, or F2?
What genetic disorder results from a sex-linked trait that affects color vision?
The genetic disorder called _______________ is known as the “free bleeders” disease.
Having three 21st chromosomes causes the genetic disorder known as _________.
A person suffering from the genetic disorder called ______________ can not digest fats.
_____________________ disease is a genetic disorder where red blood cells carry less oxygen.
Work a P1 cross for plant height in peas.
Work an F1 cross for plant height in peas.
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