AP Biology Final Project: Fish Dissection

Fish (Perch) Dissection

Background Information

The name of ‘perch’ applies to more than 6000 different species. They are found in the waters of Eurasia and North America. Names of the most common species include yellow perch, European perch, and spangled perch. Although their appearances vary by species--think golden perch and silver perch--they have an average size of about 10-20 inches and are characterized by a strong, long spine. Perch are all freshwater fish, so they are found in lakes, ponds, and rivers. Their diet may vary by size. Plankton and insect larvae are included in the diets of most, but larger perch may consume smaller fish as well.

Like most fish, perch breathe with the movement of water into and out of the gills. Water is taken in through the mouth and forced through the gills. The thin walls of the gills pass dissolved oxygen to the bloodstream, and the rest is forced out of the fish.

Perch are usually characterized by distinctive stripes along their sides. The yellow perch has dark black bands across its sides while the remainder is yellowish in color. The European cousin of this species is similar, just darker in tinge.

Major Internal and External Anatomy

 

Maxilla: the upper jaw, fixed and immovable, which serves as a clamping base for the lower jaw

Mandible: the lower jaw, movable to grasp and obtain food

Operculum: covers and protects gills, regulates the flow of water over gills

Gills: respiratory and excretory organs each formed of two layers of filaments; they enable water to exchange oxygen and ammonium as it circulates over the gills

Anal fins: stabilize the back region of the fish during motion

Urogenital pores: opening common to the genital and urinary tracts allowing the evacuation of gametes and urine

Liver: viscera that secretes bile, among other substances; bile helps digestion

Heart: muscular organ helping blood to circulate

Swim bladder: fills with oxygen; closed sac that maintains the fish at one or more pressure levels throughout the sea by secretion and absorption of gas

Stomach: dilated section of the digestive tract preceding the intestine; receives food to be digested

Intestines: section of the digestive tract between the stomach and the anus where absorption of nutrients is carried out and waste is transformed into fecal matter

Gonads: testes that produce sperm in males, ovaries that produce ova in female

Incision Guide

The bony flap that covers the gills on either side of the fish's head are called the opercula. Use scissors to remove the opercula that is on the upwards facing side when the fish is laid flat. 

Take note of the spacing between the gills. Then, cut out a single gill with the curve gill arch and the soft gill filaments attached. 

If needed, secure the fin to the dissecting pan with pins. Then, use a scalpel and/or scissors to make a rectangular cut that extends from the very end of the operculum to the beginning of the curve at the rear of the fish or the anal fins. Carefully remove this flap, ensuring it is only skin and muscle with no internal organs attached.

Locate the liver at the front of the cavity next to the gills. Remove the liver to observe the short esophagus attached to the stomach.

Dissection Procedure

Artificial Selection Lab

Artificial Selection Lab

Purpose

The purpose of this lab is to discover how the process of artificial selection is used on existing species--in this case, plant species--with varying characteristics to develop offspring with only the desired traits. By using fast-growing, lab-developed plants, we can more easily observe how artificial selection works across multiple generations.

Introduction

Artificial selection has led to many of today’s species, especially domesticated ones. The many breeds of dogs and cats were artificially selected for distinctive traits. Species of crops were also developed over many years for the most viable characteristics.

Fast Plants are plants developed by a professor at University of Wisconsin-Madison to be plants that germinate in a very short time period, only a matter of a couple of days. Not only do they develop so quickly, but they are also made to pollinate with only involvement by the researcher.

Methods

A wicking cord is threaded through the bottom of each of the three pots. Each of the pots are filled with potting mix until they are almost full. The soil is patted down firmly into each pot.

Plant six seeds into the respective pot of each type. Cover the seeds with a thin layer of soil and pat it down firmly onto the seeds.

Place the pots into the provided plastic pan, ensuring that the wicking cord extends to the reservoir below.

On the left: the three pots after the seeds were planted

Water the plants with liquid fertilizer every day. Take pictures of the three different plant varieties, observing changes in growth and plant height. Pay attention to the distinct characteristics of each plant variety.

   

Above: days five and seven of plant growth**

When flowers have developed on all of the three varieties, cotton swabs can be used to collect pollen from one flower and deposit it on another flower. Choose two varieties to cross-pollinate; the offspring of this are the testing population. The third variety would be self-pollinated as a control group.

  

Above: days fourteen and eighteen of plant growth**

After several days, seed pods will develop on the plants. Take the pods off of each plant. Be sure to label them according to which plant they came from.

Above: day twenty-four of plant growth

Allow the seeds to completely dry until they are yellow. Then, open the pods and remove the seeds. These are the seeds for the second generation of plants.

Plant these seeds in the same way as the first generation. Observe the growth of these plants over time until they develop the fully developed traits. The control group of the second generation should have the same traits as the first generation. The test group of the second generation should have combined traits from the cross-pollinated groups.

Data

We were unable to obtain accurate data about the artificial selection cross because the seeds of the second generation did not grow to full development.

Graphs & Charts

Graphs and charts were not needed for the analysis of this lab.

Discussion

The unsuccessful results of this experiment could have been due to a host of both environmental and experimental factors: lack of water, burying the seeds too deeply in the soil, too few seeds, crowding of seeds, etc. In alterations to this experiment for actual success, there could be several groups of the same three varieties so there are different opportunities for a test cross to be successful.

Although the results of this lab were not able to be analyzed, this process did provide great insight into how artificial selection is used to develop strains of species with certain traits. It also provided awareness of situations where artificial selection could be unintentionally manipulated. If plants of different varieties are too close together, pollen could be exchanged between their flowers.

Conclusion

We began the experiment being very attentive, our plants began to thrive and lived very well for a long time. We cross pollinated the three plants flowers and continued to water them until pods formed and grew to have seeds in them. Yet for some reason the pods the plants produced had very minimal seeds. To continue our experiment we planted what seeds we could scavenge from the pods after letting them dry out over the weekend.

**Note: With off days and weekends, the number of the day on which each stage of growth was observed was estimated.

Essential Knowledge 1.C.1

Alternate links:
https://video.videolicious.com/dc974a61-785c-4333-980c-fb38c92e7080 
https://www.youtube.com/watch?v=TeKJgzQY9p4

Essential knowledge 1.B.1

1. Photosynthesis in autotrophic organisms is an ancient process, which originated in some of the very first organisms to live on the Earth. As life has evolved, the process of photosynthesis has changed in some ways, but still has remained the staple metabolic process for autotrophic organisms. Considering how widely spread and deeply ingrained this process is in the history of autotrophs, it provides a significant basis for the common ancestry of organisms.

2. Though a large portion of life on Earth today does not go through the process of photosynthesis, pretty much all organisms go through cellular respiration. This process is vital to the survival of every kind of life on Earth and is conducted in essentially the same way in all of them. Considering how identical this facet of life is in every place in which it occurs, it is likely that the first organism to undergo cellular respiration eventually gave way to all the organisms in existence today.

3. The uniformity of the structure and function of DNA in all life means that, in some way, all living things are related. No species on Earth has DNA that is not made up of the same 4 nucleotides which code for the same 20 amino acids to make the proteins which determine the organisms structure and function and maintain its well being over the course of its existence. DNA is all different, but it's made up of the exact same materials and functions in the same way in everything, so all life is at least tied together in this way. DNA utilization is a common feature of every living thing, meaning that they all probably shared a similar origin.

Essential Knowledge 2.1.A

An example of an exergonic reaction is the reduction of acetylaldehyde, represented by the formula C2H4O + 2e- + 2H+ ----> C2H6O. In biological systems, this reaction is coupled with the endergonic oxidation of NADH, represented as NADH + H+ ----> NAD+ + 2e- + 2H+. The oxidation of NADH is vital for the process of cell respiration, so this reaction coupling is vital to most every organism. The combined equation for the coupled reaction is C2H4O + NADH + H+ ----> C2H6O + NAD+. Below are the energy graphs for the reduction of acetylaldehyde (left) and the oxidation of NADH (right).                                              

Essential Knowledge 1.C.1 (3D GameLab)

Essential knowledge 1.A.2: Natural selection acts on phenotypic variations in populations

21. Percentages in Light Forest and Dark Forest
In the light forest, the final color distribution of the moth population was 29% dark and 71% light. In the dark forest, the final color distribution of the moth population was 65% dark and 35% light.

22. Explain how the color of the moths increases or decreases their chances of survival.

If the moth's coloring contrasts with the moth's environment, then its chances of survival are decreased due to the moth clearly standing out to predators. If the moth's coloring blends with the moth's environment, then its chances of survival are increased due to an increased difficulty for predators to see the moth.

23. Explain the concept of "natural selection" using your moths as an example.

In the light-colored tree environment, the dark coloring phenotype for moths was selected against as it served as a selective disadvantage for the moths, since they stood out clearly to predators. Thus, natural selection favored the light coloring phenotype and that trait prevailed. In the dark-colored tree environment, the light coloring phenotype was selected against as it served as a selective disadvantage for the moths, since they stood out clearly to predators. Thus, natural selection favored the dark coloring phenotype and that trait prevailed.

24. What would happen if there were no predators in the forest? Would the colors of the moths change over time? Defend your answer.

Without predators in the forest, the colors of the moths would not change significantly over time, since there would be no motivation for the population to change. Natural selection requires some sort of obstacle for a population to face in response to which one trait provides an advantage or disadvantage to the species.

Example

One example of an evolutionary change in a population is tied to a change in its environment is the development of DDT resistance in insects. In areas where DDT has been used as an insecticide, small percentages of the insect population were resistant prior to the utilization of the chemical; after its use, only the resistant insects survived, allowing them a huge selective advantage against non-resistant insects. Since the insects' environment changed when DDT was introduced, the population was able to evolve in response to the change. Humans were the real cause of this evolutionary shift, as we introduced the chemical which altered the insects' environment and kickstarted their evolution. The impact of this evolution on the future means that the use of DDT in areas where it has been used previously may be completely ineffective if the insects evolved in response to it.