bis2b lab practical

Overall theme of Lab 1

What is diversity and how can we measure it?

What is diversity?

The number of species (species richness) and number of individuals in each of those species (species evenness) in a certain place at a certain time

How do we calculate diversity?

Using the true diversity index, a combination of species richness and species abundance

D=(p1^-p1)(p2^-p2)(p3^-p3)...(pn^-pn)

pi = the number of individuals of a species divided by the total number of individuals of all species

If D of habitat 1 is greater than D of habitat 2, what can you conclude about these two habitats?

Habitat 1 is more diverse than habitat 2. It has a higher overall species abundance and species richness

If you calculated D= 1, what does this tell you about the habitat? What must be true in order to calculate D= 1 (plug numbers in and you will see)?

This habitat has the lowest possible diversity. There is only one species in the habitat.

Transect sampling

Place a tape measurer down the middle of the habitat. Record every specimen found within a fixed distance from the line

Quadrat sampling

Divide the habitat into rectangles of known size. Either randomly select or select a set number of boxes (ex: every other box) to take samples from. Randomizing eliminates your bias.

Why do we use methods like transect and quadrat sampling?

It is too big a task to sample an entire habitat, so we split it up into multiple small sections that represent the habitat as a whole and estimate the true diversity.

What are Operational Taxonomic Unit (OTU)s and what is the value of using OTU's initially rather than formal scientific names?

What would be the value of ultimately assigning formal scientific names to your OTU's?

A non-technical name given to a group of organisms that are morphologically similar.

These names make different species easy to identify because you don't have to memorize long names that don't tell you much about what the species look like. Eventually, it would be beneficial to assign formal scientific names to your OTUs so others who read your lab reports will know what you're talking about.

What do rarefaction plots measure?

The number of individuals vs the number of species measured

What is the typical trend in rarefaction plots?

The number of individuals/species is increasing at a very high rate at first. It eventually slows down because as you sample more and more individuals, soon they will all be from species you have already recorded. The number of individuals will continue to increase but the the number of species will not.

Overall theme of Lab 2

Resource acquisition

Autotroph vs photoautotroph vs heterotroph

Troph- relating to food

Auto- self

Hetero- other, different

Autotroph- an organism that produces food for itself (ex: plants)

Photoautotroph- an organism that uses sunlight to produce food for itself (ex: plants)

Heterotroph- an organism that must consume other organisms for nutrients and energy (ex: animals)

Photosynthesis

Occurs in the chloroplast

Uses CO2, water, and sunlight, produces O2 and glucose

The products of photosynthesis are beneficial to heterotrophs that require O2 for respiration and glucose for energy.

Photoautotrophs possess pigments that absorb light that they use for photosynthesis. Different pigments capture light at different wavelengths, allowing the organism to take advantage of much of the visible spectrum.

Which pigment do most plants possess? What advantage is there to having other pigments (think about the amount of light found in different habitats)?

Plants most possess chlorophyll

If plants have other pigments, they are able to absorb the light most abundant in their habitat. For example, photoautotrophs deep in the ocean absorb different light than trees that tower over every other living thing in its habitat.

What happens to pH as photosynthesis occurs vs as respiration occurs?

As photosynthesis occurs, CO2 decreases and O2 increases. This increases the pH because CO2 is acidic.

As respiration occurs, CO2 is increasing and O2 is decreasing. This increases the pH.

What are some chemical elements most organisms require?

Carbon, oxygen, hydrogen

What is one reason water is so important to organisms?

To keep respiratory systems and other body parts/systems from drying out, serves as oxygen source for aquatic organisms

What are the products of respiration? How might autotrophs benefit from these products?

CO2

Autotrophs use CO2 for photosynthesis to create their food source

What are some adaptations in plants that make resource acquisition more efficient, and how could these have evolved?

Root hairs on plants increase surface area to increase the plants ability for water and nutrient uptake.

In cactus, the leaves were reduced to spines. This provides two functions: 1) protection from predators and 2) reduce surface area for living in very dry environments.

These adaptations evolved through natural selection. Plants that had these traits would have a higher fitness than those who didn't, allowing them to survive, reproduce, and pass on their genes among generations.

What is the general function of a root, stem, and leaf?

Root- absorb nutrients in the soil

Stem- transport nutrients from roots to leaves

Leaf- perform photosynthesis and evapotranspiration

Would you expect a plant living in a very dry environment (desert) to have leaves with a high surface area to volume ratio or a low surface area to volume ratio? To retain heat would an organisms more likely have a high surface area to volume ratio or a low surface area to volume ratio? How about for respiration?

Dry- Low SA/V ratio to reduce the amount of water loss during transpiration

Cold- Low SA/V ratio to retain more heat, and to reduce the amount of water loss during transpiration which makes them cool down

Tomato plants were grown without certain nutrients and are not healthy when deprived of their "daily nutritional requirements", so to speak. How might this affect a plant's overall ability to compete (and ultimately its relative fitness)?

If a plant wasn't getting sufficient nutrients and had low health, it would be very difficult for them to compete with healthy individuals for the same resources they all require. This would further decrease the fitness of the nutrient-deprived plant.

Why are Rhizobiumbacteria critical for the survival of plants (and even us)?

Rhizobiumbacteria fix nitrogen for plants. Plants are not able to use the N2 in the air, but the bacteria converts it into usable NO3. This is indirectly critical to us because if plants weren't able to get sufficient nutrients, we would not be able to get the O2 and nutrients we receive from plants.

What structures do plants use for energy and nutrient storage?

Roots, stems, and leaves all play a part in energy and nutrient storage

What structures to plants use for reproduction, and how?

Flowers and fruits. Flowers are used to attract pollinators, and fruits are used for seed dispersal (animals eat the fruits with seeds, poo out the seeds, and disperse them wherever they may be)

Adaptation vs acclimation

Adaptation- involves an evolutionary change that happens over generations

Acclimation- occurs within a single organism's life time

An acclimation can become an adaptation if it increases fitness and is passed on through offspring.

How do plants acclimate to environmental stimuli (light, gravity)?

The leaves of the plant will turn to face the light.

The stem of the plant will always grow up, regardless of if you turn it upside down or sideways.

What is gravitropism? Is it found in an animal or a plant? How does it allow a plant to acclimate to the environment?

Gravitropism is when a plant stem grows in the direction gravity is pulling them. This allows plants to compete for limited resources. If there was no gravity, plants would grow in the direction of where the most resources occurred.

How might the ability to acclimate be an adaptation?

Individuals that have the ability to acclimate can have higher fitness in more situations than individuals who have no ability to acclimate. This trait would be passed on.

What is the function of the digestive system in heterotrophs?

The digestive system converts food into forms that can be used by the body for growth and metabolic requirements

Herbivores eat primary producers. What is a primary producer and why are they called primary producers?

A primary producer is an organism that takes nutrients from the soil and turns it into food for themselves and primary consumers. They are called primary producers because they are the first trophic level to produce food for the rest of the community.

What do omnivores eat? Carnivores? What is an example of a carnivore?

Omnivores eat both plants and animals. Carnivores eat meat and other organisms.

Ex of a carnivore: lions

Describe the difference between a blind gut and a 2-way gut. Which one has specialized structures to aid in digestion?

A blind gut (aka two way, aka incomplete)- only has one hole that works as an entrance and exit for nutrients/waste

A one-way gut (aka complete)- has a separate entrance for nutrients and exit for waste. This type of digestive system is able to have specialized structures because food only passes through the different areas 1 time (ex: gizzard, intenstines)

Why might a digestive system have a high surface area to volume ratio?

To allow the maximum amount of nutrients to be absorbed into the body

What are micro-organism heterotrophs and how do they eat?

Some will swim around and engulf other micro-organisms through the process of phagocytosis

What are some ways animals without backbones feed? What adaptations may they have to help them capture their food?

Animals can secrete digestive enzymes onto their prey in order to digest them externally and make them easier to consume.

Define herbivore, carnivore, omnivore, detritivore, and scavenger. In what category does a cat fit? How do the teeth of a carnivore differ from an herbivore? Give an example of an animal and non-animal example of a detritivore.

Herbivore- an organism that only feeds on plant matter, do not need sharp teeth but need teeth good for grinding, usually flat

Carnivore- an organism that feeds on other animals and mainly eats meat, must have sharp, pointy teeth to help them grab their prey and rip meat

Omnivore- eats both plant and animal matter, has both sharp and flat teeth

Detritivore- an organism that feeds on dead, decaying organic matter (ex: dung beetles, fungi)

Scavenger- consume dead prey or plant material that have died from causes other than predation

What is mixotroph?

An organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other.

Describe the differences between a deposit feeder and a suspension feeder. Into which category does a humpback whale fit?

Deposit feeder- an aquatic animal that feeds on small specks of organic matter that have drifted down through the water and settled on the bottom

Suspension feeder- an animal that feeds on material (such as planktonic organisms) suspended in water and that usually has various structural modifications for straining out its food

A humpback whale is a suspension feeder.

How does a fungus feed on other organisms?

Fungi release digestive enzymes into their food and digest it externally. They absorb the food molecules that result from the external digestion.

What are hyphae and where are they found?

Fungi consists of long, thread-like structures called hyphae which surround and grow into the food source, living or dead. These hyphae can grow extremely rapidly. In 24 hours, 0.6 miles of hyphae can be produced.

How does a parasite differ from a saprotroph?

A parasite benefits at the cost of another organism, while a saprotroph eats an organism that is already dead so they are not harming it.

Do respiratory structures, in general, have a high or low surface area to volume ratio? What could be a disadvantage for having a high surface area to volume ratio as a body form?

High to increase gas exchange.

If this was an organisms entire body form, they would not be able to retain heat well.

Overall theme of Lab 3

Population growth

Review of using micrometer

The micrometer is the "ruler" used for measuring things under the microscope. It is 100 cu (calibration units) long.

Steps

1. Set the magnification knob to 2 do not change this during calibration

2. Place a 3x5 index card on the stage. Place the "ruler" on top of it, with the lettering right side up. Make sure the ruler is in focus.

*The bottom of the ruler is marked with black lines 0.5 mm apart from each other, you use these numbers for calibration.

3. Look through the right eye piece with your right eye (close your left eye). Shift the ruler until the bottom of the ruler is parallel with the micrometer scale (in the eye piece) and the bottom left corner of the ruler is directly above the 0 mark on the micrometer

4. (Without moving the ruler), locate the fourth mark from the left on the bottom of the ruler and estimate the position of the center of the fourth mark. Record the number of cu's at this location

5. Convert the units in cu to mm

*Conversion factor: c=length of object in mm/length of object in cu

*Length of object in mm always = 2mm

6. Multiply this conversion factor by any measurement in cu to find its length in mm

Why must you come up with a new calibration for each level of magnification?

The cu will be bigger if the microscope is more magnified, and smaller if it is less magnified

What is the difference between density independence and density dependence?

Density dependent—the pop. size plays a role as to how the population is affected (competition is usually a density dependent factor).

Density independent—it does not matter what the population size is in order for there to be an effect on the population (for example, a fire is a density independent event).

What can control birth rates or death rates in a population? How might emigration or immigration affect populations?

Birth/death rates can be controlled by food availability, predators, etc. Immigration increases population size and emigration decreases it.

At high densities, the Blepharisma that you looked at in lab turns into a cannibalistic form. Is this a density dependant or independent event? What might drive this organism to start feeding on others of its kind?

Density dependent. When the population increases beyond its carrying capacity, individuals run out of resources and turn to cannibalism to fuel their need for food and reduce competition.

In this lab you saw the formula Nt=Nt-1 + B - D. In your own words describe what each term represents. What would happen to Nt if B is greater than D? If B is less than D? If B = D?

Nt= population size at time (t)

B= births

D= deaths

If B > D, Nt would increase

If B < D, Nt would decrease