Forensics C

[Unome]

On previous years' threads people have said the nationals test is ridiculously long; over 200 questions. How...how do you even get through half of it? Our state test was around 35 questions plus a write-up, and we barely had time to finish. Although from the previous threads it sounds like each individual question is easier, like some basic chemical reaction and identifying evidence with certain suspects.

You don't get through half of it; you get through 70% of it (if you're exceptionally good) and if you managed your time well, you have a shot at a medal (at least this is my understanding of it).

[daydreamer0023]

Does anyone know if they provide microscopic images at nationals of the different fibers at the crime scene to help with identification? Or do you have to tell by feel/burn tests (if this is the case, then what are some distinct physical charecteristics if we can't use microscope pictures)?

Also, what is the difference, in pictures, between human, mammal, avian, and reptile blood? I don't quite get that. A simple explanation of mass spec would help too - I've looked online and found some nice websites, but most of it goes over my head.

[sciduck]

Does anyone know if they provide microscopic images at nationals of the different fibers at the crime scene to help with identification? Or do you have to tell by feel/burn tests (if this is the case, then what are some distinct physical characteristics if we can't use microscope pictures)?

Also, what is the difference, in pictures, between human, mammal, avian, and reptile blood? I don't quite get that. A simple explanation of mass spec would help too - I've looked online and found some nice websites, but most of it goes over my head.

I have never been to Nationals, but one website says:
-know how to do a burn test on only one strand of fiber
-don’t use more than one strand, which is more difficult than a ball
-be prepared to make an identification using a microscope making your own wet mount (this will NOT already be done for you)
Source: http://www.raleighcharterhs.org/student ... ensics.asp

As for blood:
-Mammalian blood cells don't have nuclei and organelles for two reasons. The first is an adaption to increase oxygen carrying potential by making more room for hemoglobin. The second is increased flexibility to pass through small capillaries.
-Human blood cells are spherical.
-Avian blood cells are very elliptical and have nuclei. Imagine pink rice with nuclei.
-Fish blood cells have nuclei and are bigger than human blood cells, but smaller than frog blood cells. They also have less types of lymphocytes than humans.
-I don't know how to tell the difference between human blood and other mammals (with the exception of camels) and I also can't tell the difference between reptiles and amphibians (amphibian blood cells maybe rounder? Might just be my specific set of pictures, I don't really know). I just printed out some pictures and hoped it wouldn't show up, but let me know if you find out how.

Good luck at Nationals!

[justgreene]

How does TLC work at nationals? Are we supposed to conduct it ourselves like we would for paper chromatography? Also can somebody explain the short vs. long wavelength UV radiation stuff for TLC fluorescence that I've seen on past nationals tests.

[pikachu4919]

On previous years' threads people have said the nationals test is ridiculously long; over 200 questions. How...how do you even get through half of it? Our state test was around 35 questions plus a write-up, and we barely had time to finish. Although from the previous threads it sounds like each individual question is easier, like some basic chemical reaction and identifying evidence with certain suspects.

You don't get through half of it; you get through 70% of it (if you're exceptionally good) and if you managed your time well, you have a shot at a medal (at least this is my understanding of it).

Lol this seems a bit late since Nats has passed already, but splitting the work with your partner always works. But lol Unome is essentially correct on what he/she said.

Does anyone know if they provide microscopic images at nationals of the different fibers at the crime scene to help with identification? Or do you have to tell by feel/burn tests (if this is the case, then what are some distinct physical characteristics if we can't use microscope pictures)?

Also, what is the difference, in pictures, between human, mammal, avian, and reptile blood? I don't quite get that. A simple explanation of mass spec would help too - I've looked online and found some nice websites, but most of it goes over my head.

I have never been to Nationals, but one website says:
-know how to do a burn test on only one strand of fiber
-don’t use more than one strand, which is more difficult than a ball
-be prepared to make an identification using a microscope making your own wet mount (this will NOT already be done for you)
Source: http://www.raleighcharterhs.org/student ... ensics.asp

As for blood:
-Mammalian blood cells don't have nuclei and organelles for two reasons. The first is an adaption to increase oxygen carrying potential by making more room for hemoglobin. The second is increased flexibility to pass through small capillaries.
-Human blood cells are spherical.
-Avian blood cells are very elliptical and have nuclei. Imagine pink rice with nuclei.
-Fish blood cells have nuclei and are bigger than human blood cells, but smaller than frog blood cells. They also have less types of lymphocytes than humans.
-I don't know how to tell the difference between human blood and other mammals (with the exception of camels) and I also can't tell the difference between reptiles and amphibians (amphibian blood cells maybe rounder? Might just be my specific set of pictures, I don't really know). I just printed out some pictures and hoped it wouldn't show up, but let me know if you find out how.

Good luck at Nationals!

Although the rules say to know it, Woz generally doesn't use microscope images for hair. I think she used to, but she hasn't on all the tests I've seen recently. She does use them for blood if she includes animal blood as part of the crime scenario.

How does TLC work at nationals? Are we supposed to conduct it ourselves like we would for paper chromatography? Also can somebody explain the short vs. long wavelength UV radiation stuff for TLC fluorescence that I've seen on past nationals tests.

Lol also a bit late for this one, but yeah you do it yourself. Woz always makes you do it yourself. And the short vs long wavelength is a setting on the blacklight, and I think you just see if it glows. Tbh at nats I actually skipped most of the TLC questions bc honestly if you get enough ID's and trivia questions right, it'll make up for it anyways.

[Magikarpmaster629]

Pickachu4919, congrats on your nationals medal! I should have said hi to you during the Forensics event since we took it at the same time, but I forgot to.

Anyway, at nationals were there duplicates of any of the powders? I think I put down three different powders twice, but my powder IDing was super sketchy.

[guilt]

Yes, there were duplicates of multiple powders. I think LiCl was one of them, can't remember the others.

Also, yes forensics tests (especially and specifically nats) are long, but not impossible the finish. My partner and I were able to finish the nats test/do relatively well (minus mass spec cause we accidentally skipped it and forgot to go back) by having pre assigned sections. I did the powders and polymers while my partner did the other crime scene stuff. Then I wrote up the crime scene analysis while my partner did the trivia questions.

[pikachu4919]

Pickachu4919, congrats on your nationals medal! I should have said hi to you during the Forensics event since we took it at the same time, but I forgot to.

Anyway, at nationals were there duplicates of any of the powders? I think I put down three different powders twice, but my powder IDing was super sketchy.

Thanks! 16th is really good too ;D Lol tbh I was thinking the exact same thing that you did Oh well... I'll see if I can get onto the volunteer crew next year for nats tho! And yeah, I think I remember my partner saying she saw red flames for two of the powders. Lol I remember one of my coaches said that one time when he was a forensics supervisor, he had them identify six powders with three of them being sodium bicarbonate. I told him that was evil

Yes, there were duplicates of multiple powders. I think LiCl was one of them, can't remember the others.

Also, yes forensics tests (especially and specifically nats) are long, but not impossible the finish. My partner and I were able to finish the nats test/do relatively well (minus mass spec cause we accidentally skipped it and forgot to go back) by having pre assigned sections. I did the powders and polymers while my partner did the other crime scene stuff. Then I wrote up the crime scene analysis while my partner did the trivia questions.

Niceeeee Where are you from again?

[19sawickin]

This was probably mentioned early in the forum, but does anybody know where to find good forensics kits that include blood to test as well as large plastic samples (not just the granular plastic samples) and some powders?

[samlan16]

This was probably mentioned early in the forum, but does anybody know where to find good forensics kits that include blood to test as well as large plastic samples (not just the granular plastic samples) and some powders?

Large plastic samples can be drawn from your recycle bin; just make sure that you note the recycling code. (Exceptions: PMMA and PC must be found elsewhere. PC may be in your glasses; PMMA is Plexiglas, which you could probably find at a hardware store.) Powders from the list can pretty much be bought in bulk online or around town. You can get some things at the store- sucrose, flour, cornstarch, maybe even glucose at a pharmacy. Get creative.