ABSTRACT
To feed on materials that are healthy for them, flies (order Diptera) use taste
receptors on their tarsi to find sugars to ingest. We examined the ability of blowflies to
taste monosaccharide and disaccharide sugars as well as saccharin. To do this, we attached
flies to the ends of sticks and lowered their feet into solutions with different concentrations
of these she
saccharin we use is actually the sodium salt of saccharin, and they reject salt solutions.
Overall, our results show that flies are able to taste and choose foods that are good for
them.
INTRODUCTION
All animals rely on senses of taste and smell to find acceptable food for survival.
Chemoreceptors are found in the taste buds on the tongue in humans (Campbell, 2008), for
example, for tasting food. Studies of sensory physiology have often used insects as
experimental subjects because insects can be manipulated with ease and because their
sensory-response system is relatively simple (E. Williams, personal communication). Flies
are able to taste food by walking on it (Dethier, 1963). Hollow hairs around the proboscis
and tarsi contain receptor neurons that can distinguish among water, salts, and sugars, and
flies can distinguish among different sugars (Dethier, 1976). These traits enable them to
f
The flies responded to sucrose at a lower concentration than they did of glucose, and they
didn’t respond to saugars. We counted a positive response when they lowered their proboscis to feed.
The flies responded to sucrose at a lower concentration than they did of glucose, and they
didn’t respond to saccharin at all. Our results show that they taste larger sugar molecules
more readily than they do smaller ones. They didn’t feed on saccharin because tccharin at all. Our results show that they taste larger sugar molecules
more readily than they do smaller ones. They didn’t feed on saccharin because tax we
rubbed on the sticks. Then we made a dilution series of glucose, maltose, and sucrose in
one-half log molar steps (0.003M, 0.01M, 0.03M, 0.1M, 0.3M, and 1M) from the 1M
concentrations of the sugars we were given. We tested the flies’ sensory perception by
giving each fly the chance to feed from each sugar, starting with the lowest concentration
and working up. We rinsed the flies between tests by swishing their feet in distilled water.
We counted a positive response whenever a fly lowered its proboscis. To ensure that
positive responses were to sugars and not to water, we let them drink distilled water before
each test. See the lab handout Taste Reception in Flies (Biology Department, 2000) for
details.
RESULTS
Flies responded to high concentrations (1M) of sugar by lowering their probosces
and feeding. The threshold concentration required to elicit a positive response from at
least 50% of the flies was lowest for sucrose, while the threshold concentration was highest
for glucose (Fig. 1). Hardly any flies responded to saccharin. Based on the results from all
Fly lab report p. 4 the lab groups together, there was a major difference in the response of flies to the sugars
and to saccharin (Table 1). When all the sugars were considered together, this difference
was significant (t = 10.46, df = 8, p < .05). Also, the response of two flies toind necessary nutrition.
Fly lab report p. 3 In this experiment we tested the ability of the blowfly Sarcophaga bullata to taste
different sugars and a sugar substitute, saccharin. Because sucrose is so sweet to people, I
expected the flies to taste lower concentrations of sucrose than they would of maltose and
glucose, sugars that are less sweet to people. Because saccharin is also sweet tasting to
people, I expected the flies to respond positively and feed on it as well.
METHODS
We stuck flies to popsickle sticks by pushing their wings into a sticky wugars. We counted a positive response when they lowered their proboscis to feed. saccharin was
not statisticallGoals:
Students will create a brine shrimp tank with one variable changed.
Students will be able to describe how they set up their brine shrimp tank.
Students will be able to explain why they set up their tank the way they did.
Objectives: (national or state)
3.F.1.b Explain that organisms live in habitats that provide their basic needs.
Observation and description of minute organisms in their habitats (MCPS objective)
Materials: (variety, internet, articles, books…)
Brine shrimp eggs
Plastic tank
Water
Salt
Straws
Brine Shrimp. How do they survive in such an extreme environment? - Great Salt Lake Ecosystem Program http://wildlife.utah.gov/gsl/brineshrimp/survive.php
Class blog at http://mrscrum2ndgrade.blogspot.com
ELMO projector
Lesson:
Ask students to discuss with a talking partner what we learned about brine shrimp yesterday. For students who need assistance prompt them to share about the stages, what the eggs look like, and where they live.
Allow students time to share about what they remember about brine shrimp and share what is listed on the K part of the class KWL chart.
Explain that today we will set up our brine shrimp habitat. Ask students to think about and discuss with their partner a habitat and what brine shrimp might need in their habitat.
Read the article, Brine Shrimp, How do they survive in such an extreme environment? , which will be projected on the board using the ELMO projector. As you read the article talk with the class about what the shrimp will need in their habitat we are creating.
After reading the article, on the board write down the components of each brine shrimp habitat (room temperature water, 2 tablespoons of salt, 1 tablespoon of brine shrimp eggs, and a straw to aerate the water).
Explain to students that in their table groups they will change one component, either making the water warmer or colder, adding more or less salt, or keeping the tank in full light or dark.
Allow each table group time to discuss which component they want to change and why they chose to change it. While students are doing this circulate to monitor groups and how each student is contributing to the group discussion.
After each table seems to know what their plan is create a class chart with what each table will be changing.
Have one student from each group come up and get their materials for their brine shrimp tank and allow groups time to assemble. Walk around assisting as needed. Remind students to keep everything else as it’s listed on the board, except for the one item they are changing.
When tanks have been assembled students will get out their brine shrimp journals and draw a picture of their tank and write a description of what was added to their habitat, including which component they changed.
Ask students to discuss with their table and record in their journals why changing the component they did may help more brine shrimp to grow.
Explain that students will now create a picture which will be uploaded to the class blog so all of the 2nd grade classes in the school can share and see each other’s data.
Students in each group will then share what they wrote in their journals and the group will either choose one way they think shows what they did the best, or will combine multiple ideas to create a separate drawing and short description of what they changed in their tank and why.
Later the teacher will scan and upload each group’s pictures to the class blog.
Have each group share their picture and description on the ELMO projector with the class.
Inquiry:
What might brine shrimp need in their habitat?
Why would changing the component you did help more brine shrimp to grow?
What is the best way to show your tank and explain what component you changed so that other classes can understand?
Differentiation:
Students will have a list of vocabulary to help them with their discussion and writing.
Teacher will prompt students who have difficulty writing to add more details.
Students will be able to draw and write in their journals.
Students will be able to touch and feel the components going into their habitat.
Students will be drawing and writing the information that will then be scanned and posted to the blog, as it would be very difficult and time consuming for 2nd grade students to type the information.
Assessment:
Students will be assessed using a checklist consisting of the following bullets:
I shared and discussed ideas with my group
My group changed one aspect of the habitat conditions (Examples: temperature, amount of salt, light or dark)
I drew a picture of my brine shrimp habitat
I explained how I changed my tank (Examples: temperature, amount of salt, light or dark)
I explained why my group chose to change the tank the way we did.
Students will be given a copy of the checklist at the beginning of the lesson. While students are working, the teacher will walk around the classroom and observe how each student is collaborating with their group. Journals will be looked at after the lesson to check for other items on the checklist.
y different from zero (t = 1.12, df = 8, n.s.).
DISCUSSION
concentration than that for maltose. This might also be the reason why sucrose tastes so
sweet to people.
My other hypothesis was not supported, however, because the flies did not respond
positively to saccharin. The sweetener people use is actually the sodium salt of saccharic
acid (Budavari, 1989). Even though it tastes 300 to 500 times as sweet as sucrose to
people (Budavari, 1989), flies taste the sodium and so reject saccharin as a salt. Two flies
did respond positively to saccharin, but the response of only two flies is not significant,
and the lab group that got the positive responses to saccharin may not have rinsed the flies
Fly lab report p. 5 off properly before the test.
Flies taste food with specific cells on their tarsal hairs. Each hair has, in addition to
a mechanoreceptor, five distinct cells – alcohol, oil, water, salt, and sugar – that determine
its acceptance or rejection of the food (Dethier, 1975). The membranes located on the tarsi
are the actual functional receptors since it is their depolarization that propagates the
stimulus to the fly (Dethier, 1975). Of the five cells, stimulation of the water and sugar
cells induce feeding, while stimulation of the salt, alcohol, and oil receptors inhibit
feeding. More specifically, a fly will reject food if the substrate fails to stimulate the sugar
or water receptors, stimulates a salt receptor, or causes a different message from normal
(e.g., salt and sugar receptors stimulated concurrently) (Dethier 1963).
Flies accept sugars and reject salts as well as unpalatable compounds like alkaloids
(Dethier & Bowdan, 1989). This selectivity is a valuable asset to a fly because it helps the
fly recognize potentially toxic substances as well as valuable nutrients (H. Cramer,
personal communication). Substances such as alcohols and salts could dehydrate the fly
and have other harmful effects on its homeostasis (Dethier, 1976). Thus, P_ I liked that the students were given the opportunity to represent their finding with a picture and caption, a creative headline as well as a summary. Clearly this curriculum offers students with different learning styles to have an opportunity to shine. This allows for several opportunities for perception, language, and comprehension. The choices and different forms for expression as well as the group component promote
communication, and enhance executive functioning skills. I found the engagement piece of your lesson similar to Mr. Garcia’s idea to have students write their articles for the student newspaper (http://www.cast.org/teachingeverystudent/casestories/cs2/index.cfm?page_id=37)
Q-How well did the lesson plan met the following criteria #’s 4, 5, and 6?
The students were provided the opportunity to communicate but did accommodate for their potential needs for physical action. I am not sure that the teacher’s presentation methods (I noticed student readings to be the main focus) varied opportunities for providing information or recruiting student interest.
P-In order to polish the activity, students could present their findings in a second class in which they were asked to put on a brief skit. They could create a presentation utilizing many of the technological tools presented in the class. This would promote the use of technology as well as help with kinesthetic learning.I’ve made some adjustments to the lesson to incorporate a UDL perspective into the lesson plan. Instead of having students use the Nystrom Atlas of United States History to answer questions. I’ve decided to pull the map showing where the battles of the Civil War took place onto a smart board. This will allow students to be more engaged, and I can use the map to point to different areas of focus that would help students answer the questions. For students who do not like to work independently or requires some support, I’ve allowed students to work in small groups. I will provide a text-to-speech tool for students who are struggling with reading and comprehension of the materials. I will also provide small group support to these students to make sure that they complete the activity.
flies are well
adapted to finding food for their own survival.
The results supported my first hypothesis that sucrose would be the most easily
detectable sugar by the flies. Flies show a selectivity of response to sugars based on
molecular size and structure. Glucose, the smallest of the three sugars, is a
monosaccharide. The threshold value of glucose was the highest in this experiment
because a higher concentration of this small sugar was needed to elicit a positive response.
Maltose and sucrose are both disaccharides but not with the same molecular weight or
composition. It has been shown that flies respond better to alpha-glucosidase derivatives
than to beta-glucosidase derivatives (Dethier 1975). Because sucrose is an alphaglucosidase
derivative, it makes sense that the threshold value for sucrose occurs at a lower
To feed on materials that are healthy for them, flies (order Diptera) use taste
receptors on their tarsi to find sugars to ingest. We examined the ability of blowflies to
taste monosaccharide and disaccharide sugars as well as saccharin. To do this, we attached
flies to the ends of sticks and lowered their feet into solutions with different concentrations
of these she
saccharin we use is actually the sodium salt of saccharin, and they reject salt solutions.
Overall, our results show that flies are able to taste and choose foods that are good for
them.
INTRODUCTION
All animals rely on senses of taste and smell to find acceptable food for survival.
Chemoreceptors are found in the taste buds on the tongue in humans (Campbell, 2008), for
example, for tasting food. Studies of sensory physiology have often used insects as
experimental subjects because insects can be manipulated with ease and because their
sensory-response system is relatively simple (E. Williams, personal communication). Flies
are able to taste food by walking on it (Dethier, 1963). Hollow hairs around the proboscis
and tarsi contain receptor neurons that can distinguish among water, salts, and sugars, and
flies can distinguish among different sugars (Dethier, 1976). These traits enable them to
f
The flies responded to sucrose at a lower concentration than they did of glucose, and they
didn’t respond to saugars. We counted a positive response when they lowered their proboscis to feed.
The flies responded to sucrose at a lower concentration than they did of glucose, and they
didn’t respond to saccharin at all. Our results show that they taste larger sugar molecules
more readily than they do smaller ones. They didn’t feed on saccharin because tccharin at all. Our results show that they taste larger sugar molecules
more readily than they do smaller ones. They didn’t feed on saccharin because tax we
rubbed on the sticks. Then we made a dilution series of glucose, maltose, and sucrose in
one-half log molar steps (0.003M, 0.01M, 0.03M, 0.1M, 0.3M, and 1M) from the 1M
concentrations of the sugars we were given. We tested the flies’ sensory perception by
giving each fly the chance to feed from each sugar, starting with the lowest concentration
and working up. We rinsed the flies between tests by swishing their feet in distilled water.
We counted a positive response whenever a fly lowered its proboscis. To ensure that
positive responses were to sugars and not to water, we let them drink distilled water before
each test. See the lab handout Taste Reception in Flies (Biology Department, 2000) for
details.
RESULTS
Flies responded to high concentrations (1M) of sugar by lowering their probosces
and feeding. The threshold concentration required to elicit a positive response from at
least 50% of the flies was lowest for sucrose, while the threshold concentration was highest
for glucose (Fig. 1). Hardly any flies responded to saccharin. Based on the results from all
Fly lab report p. 4 the lab groups together, there was a major difference in the response of flies to the sugars
and to saccharin (Table 1). When all the sugars were considered together, this difference
was significant (t = 10.46, df = 8, p < .05). Also, the response of two flies toind necessary nutrition.
Fly lab report p. 3 In this experiment we tested the ability of the blowfly Sarcophaga bullata to taste
different sugars and a sugar substitute, saccharin. Because sucrose is so sweet to people, I
expected the flies to taste lower concentrations of sucrose than they would of maltose and
glucose, sugars that are less sweet to people. Because saccharin is also sweet tasting to
people, I expected the flies to respond positively and feed on it as well.
METHODS
We stuck flies to popsickle sticks by pushing their wings into a sticky wugars. We counted a positive response when they lowered their proboscis to feed. saccharin was
not statisticallGoals:
Students will create a brine shrimp tank with one variable changed.
Students will be able to describe how they set up their brine shrimp tank.
Students will be able to explain why they set up their tank the way they did.
Objectives: (national or state)
3.F.1.b Explain that organisms live in habitats that provide their basic needs.
Observation and description of minute organisms in their habitats (MCPS objective)
Materials: (variety, internet, articles, books…)
Brine shrimp eggs
Plastic tank
Water
Salt
Straws
Brine Shrimp. How do they survive in such an extreme environment? - Great Salt Lake Ecosystem Program http://wildlife.utah.gov/gsl/brineshrimp/survive.php
Class blog at http://mrscrum2ndgrade.blogspot.com
ELMO projector
Lesson:
Ask students to discuss with a talking partner what we learned about brine shrimp yesterday. For students who need assistance prompt them to share about the stages, what the eggs look like, and where they live.
Allow students time to share about what they remember about brine shrimp and share what is listed on the K part of the class KWL chart.
Explain that today we will set up our brine shrimp habitat. Ask students to think about and discuss with their partner a habitat and what brine shrimp might need in their habitat.
Read the article, Brine Shrimp, How do they survive in such an extreme environment? , which will be projected on the board using the ELMO projector. As you read the article talk with the class about what the shrimp will need in their habitat we are creating.
After reading the article, on the board write down the components of each brine shrimp habitat (room temperature water, 2 tablespoons of salt, 1 tablespoon of brine shrimp eggs, and a straw to aerate the water).
Explain to students that in their table groups they will change one component, either making the water warmer or colder, adding more or less salt, or keeping the tank in full light or dark.
Allow each table group time to discuss which component they want to change and why they chose to change it. While students are doing this circulate to monitor groups and how each student is contributing to the group discussion.
After each table seems to know what their plan is create a class chart with what each table will be changing.
Have one student from each group come up and get their materials for their brine shrimp tank and allow groups time to assemble. Walk around assisting as needed. Remind students to keep everything else as it’s listed on the board, except for the one item they are changing.
When tanks have been assembled students will get out their brine shrimp journals and draw a picture of their tank and write a description of what was added to their habitat, including which component they changed.
Ask students to discuss with their table and record in their journals why changing the component they did may help more brine shrimp to grow.
Explain that students will now create a picture which will be uploaded to the class blog so all of the 2nd grade classes in the school can share and see each other’s data.
Students in each group will then share what they wrote in their journals and the group will either choose one way they think shows what they did the best, or will combine multiple ideas to create a separate drawing and short description of what they changed in their tank and why.
Later the teacher will scan and upload each group’s pictures to the class blog.
Have each group share their picture and description on the ELMO projector with the class.
Inquiry:
What might brine shrimp need in their habitat?
Why would changing the component you did help more brine shrimp to grow?
What is the best way to show your tank and explain what component you changed so that other classes can understand?
Differentiation:
Students will have a list of vocabulary to help them with their discussion and writing.
Teacher will prompt students who have difficulty writing to add more details.
Students will be able to draw and write in their journals.
Students will be able to touch and feel the components going into their habitat.
Students will be drawing and writing the information that will then be scanned and posted to the blog, as it would be very difficult and time consuming for 2nd grade students to type the information.
Assessment:
Students will be assessed using a checklist consisting of the following bullets:
I shared and discussed ideas with my group
My group changed one aspect of the habitat conditions (Examples: temperature, amount of salt, light or dark)
I drew a picture of my brine shrimp habitat
I explained how I changed my tank (Examples: temperature, amount of salt, light or dark)
I explained why my group chose to change the tank the way we did.
Students will be given a copy of the checklist at the beginning of the lesson. While students are working, the teacher will walk around the classroom and observe how each student is collaborating with their group. Journals will be looked at after the lesson to check for other items on the checklist.
y different from zero (t = 1.12, df = 8, n.s.).
DISCUSSION
concentration than that for maltose. This might also be the reason why sucrose tastes so
sweet to people.
My other hypothesis was not supported, however, because the flies did not respond
positively to saccharin. The sweetener people use is actually the sodium salt of saccharic
acid (Budavari, 1989). Even though it tastes 300 to 500 times as sweet as sucrose to
people (Budavari, 1989), flies taste the sodium and so reject saccharin as a salt. Two flies
did respond positively to saccharin, but the response of only two flies is not significant,
and the lab group that got the positive responses to saccharin may not have rinsed the flies
Fly lab report p. 5 off properly before the test.
Flies taste food with specific cells on their tarsal hairs. Each hair has, in addition to
a mechanoreceptor, five distinct cells – alcohol, oil, water, salt, and sugar – that determine
its acceptance or rejection of the food (Dethier, 1975). The membranes located on the tarsi
are the actual functional receptors since it is their depolarization that propagates the
stimulus to the fly (Dethier, 1975). Of the five cells, stimulation of the water and sugar
cells induce feeding, while stimulation of the salt, alcohol, and oil receptors inhibit
feeding. More specifically, a fly will reject food if the substrate fails to stimulate the sugar
or water receptors, stimulates a salt receptor, or causes a different message from normal
(e.g., salt and sugar receptors stimulated concurrently) (Dethier 1963).
Flies accept sugars and reject salts as well as unpalatable compounds like alkaloids
(Dethier & Bowdan, 1989). This selectivity is a valuable asset to a fly because it helps the
fly recognize potentially toxic substances as well as valuable nutrients (H. Cramer,
personal communication). Substances such as alcohols and salts could dehydrate the fly
and have other harmful effects on its homeostasis (Dethier, 1976). Thus, P_ I liked that the students were given the opportunity to represent their finding with a picture and caption, a creative headline as well as a summary. Clearly this curriculum offers students with different learning styles to have an opportunity to shine. This allows for several opportunities for perception, language, and comprehension. The choices and different forms for expression as well as the group component promote
communication, and enhance executive functioning skills. I found the engagement piece of your lesson similar to Mr. Garcia’s idea to have students write their articles for the student newspaper (http://www.cast.org/teachingeverystudent/casestories/cs2/index.cfm?page_id=37)
Q-How well did the lesson plan met the following criteria #’s 4, 5, and 6?
The students were provided the opportunity to communicate but did accommodate for their potential needs for physical action. I am not sure that the teacher’s presentation methods (I noticed student readings to be the main focus) varied opportunities for providing information or recruiting student interest.
P-In order to polish the activity, students could present their findings in a second class in which they were asked to put on a brief skit. They could create a presentation utilizing many of the technological tools presented in the class. This would promote the use of technology as well as help with kinesthetic learning.I’ve made some adjustments to the lesson to incorporate a UDL perspective into the lesson plan. Instead of having students use the Nystrom Atlas of United States History to answer questions. I’ve decided to pull the map showing where the battles of the Civil War took place onto a smart board. This will allow students to be more engaged, and I can use the map to point to different areas of focus that would help students answer the questions. For students who do not like to work independently or requires some support, I’ve allowed students to work in small groups. I will provide a text-to-speech tool for students who are struggling with reading and comprehension of the materials. I will also provide small group support to these students to make sure that they complete the activity.
flies are well
adapted to finding food for their own survival.
The results supported my first hypothesis that sucrose would be the most easily
detectable sugar by the flies. Flies show a selectivity of response to sugars based on
molecular size and structure. Glucose, the smallest of the three sugars, is a
monosaccharide. The threshold value of glucose was the highest in this experiment
because a higher concentration of this small sugar was needed to elicit a positive response.
Maltose and sucrose are both disaccharides but not with the same molecular weight or
composition. It has been shown that flies respond better to alpha-glucosidase derivatives
than to beta-glucosidase derivatives (Dethier 1975). Because sucrose is an alphaglucosidase
derivative, it makes sense that the threshold value for sucrose occurs at a lower