bio lab exam

Question 1

benedict test

Answer 1

used to test for simple sugars: mono and disachharide.
- the sample is heated in the presence of copper sulfate under basic alkaline conditions.
- no sugar: blue
- sugar: green, yellow, orange, red, brown depending on amount of sugar present

Question 2

iki test

Answer 2

• test for starch present
• reagant is iodine dissolved in potassium iodide.
• if starch is present: blue/black
• no starch: yellow/orange

Question 3

biuret

Answer 3

test for polypeptides/proteins
- koh is added to raise the ph to alkaline. in this alkaline environment, copper sulfate reacts with peptide bonds to produce a purple color.
- blue: negative test for protein
- violet: positive test for protein

Question 4

what is a substrate

Answer 4

the reactant an enzyme acts on is the enzyme substrate, forming the enzyme substrate complex. only a small region of the enzyme binds to the substrate called the active site

Question 5

what is catalase and where is it found

Answer 5

catalasee is an enzyme, it is found in high amounts in the liver, it breaks down hydrogen peroxide into water ad oxygen.
work best at certain ranges: optimal range is 7-8 ph.

Question 6

what did we use in the class for the catalase?

Answer 6

liver extract: bostaurus, it contains catalase

Question 7

what is fermentation?

Answer 7

fermentation is a process that allows cells to produce atp without using oxygen. it begins with the breakdown of glucose into pyruvate and then it is converted into either lactic acid or ethanol and co2.

Question 8

why is fermentation important?

Answer 8

it can generate atp which is essential for survivial in low oxygen environments or during short bursts of activity. it keeps muscles working during intense exercise when oxygen cant be delivered fast enough to support them.

Question 9

what is bakers yeast?:

Answer 9

saccharomyces cervisae
- alcohol fermenter
- breaks down sucrose into ethanol and carbon dioxide. the carbon dioxide causes bubbles to form which is responsible for the rising of the dough in baking. the ethanol evaporates.

Question 10

what does a high vs low froth height tell you?

Answer 10

the more sucrose the yeast consumes. the more carbon dioxide it will produce, leading to more froth forming.

Question 11

what are pigments?

Answer 11

organic molecules that give color to things, example: pigments make leaves appear green and flower petals have their attractive colors.

Question 12

what are the 3 pigments in plants and tell me about them

Answer 12

found in the thylakoid membranes of chloroplasts:
- chlorophyll a: primary pigment: it absorbs light best at red and blue wavelength and least at green wavelength, it reflects the green light which is what gives the leaves its green color.
- chlorophyll b: accessory pigment. it abosrbs light at red orange and blue wavelengths.
- carotene: absorb best at blue and green. reflects orange yellow red.
chlorophyll a production decreases during fall which is why carotene stats becominging mroe visible

Question 13

what is the leaf used for photosynthesis lab and what is happening in this lab?

Answer 13

used spinach: spinacia oleracea
- in this lab we used oxygen production to assess the rate of photosynthess. first we removed the oxygen from the leaf disks and put them in water, taking the oxygen led them to sink. next they were exposed to different wavelengths to see which would result in the fastest rate of photosynthesis, leading to them producing oxygen, and rising again.
- baking soda is added to the water to increase the amount of co2 in it, because that is needed for photosynthesis to occur.

Question 14

what is photosynthesis?

Answer 14

photosynthesis is the process by which plants use light energy co2 and water to produce glucose and oxygen

Question 15

which microscope can and cant see the details of the cell

Answer 15

• compound microscope you cant see the very little things but transmission electron microscope, you can see individual molecules and very small organelles such as ribosomes.

Question 16

field diameters:

Answer 16

40x: 4.3
100x: 1.85
400x: 0.40

Question 17

how to find actual size?

Answer 17

field diameter/number of objects in the field.
example: imagine the length of a paraceium would fit 2 times and the total magnification is 400x. the actual size would be 0.40/2=0.20mm

Question 18

where does mitosis occur mainly in plants?

Answer 18

apical meristem: responsible for lenghting of plant at roots and shoots. primaru growth
lateral meristem: responsible for thickening of the plant secondary growth

Question 19

in this lab we will be examining?

Answer 19

apical meristem in roots using a root tip.
- using this because it lacks chloroplast which can make it hard to see the chromsomes

Question 20

where is the region of mitotic cell division in a growing root?

Answer 20

just behind the root cap.

Question 21

what is the stain used?

Answer 21

aceto orcein: stains the chromosomes dark and the other cellular components lightly

Question 22

after the slide is prepared effectively, what color will it be

Answer 22

the nuclear material will be stained a deep purple and the cytoplasm will be pale pink

Question 23

what is interphase?

Answer 23

not. apart of mitosis but it is the longest part of the cell cycle: g1 s and g2

Question 24

by the end of interphase?

Answer 24

the cell has two full sets of chromosomes and ready for mitosis

Question 25

prophase?

Answer 25

the chromosomes condense into visible chromosomes that are made up of two sister chromatids held together at the centromere
- nuclear envelope breaks down
- nucleolus disaappears

Question 26

metaphase?

Answer 26

chromosomes align along the metaphase plate. the spindle fibers from the centrosomes attach to the centromeres

Question 27

anaphase?

Answer 27

sister chromatids separate and pulled towards opposite ends of the pole from the spindle fibers

Question 28

telophase?

Answer 28

the nuclear envelope reforms creating two nucleli, the chromosomes decondense, spindle disappears

Question 29

fruit fly?

Answer 29

drosophila melanogaster

Question 30

life cycle of fruit fly

Answer 30

live for under two weeks but a single mating produces several 100 offspring

Question 31

how many chromosomes does a fruit fly have

Answer 31

4 pairs of chromosomes, 3 pairs of autosomal chromosomes, and one pair of sex chromosomes

Question 32

normal wild type fruit fly has which color eyes?

Answer 32

red eyes

Question 33

what does reciprocal cross mean

Answer 33

same phenotypes are used for the two crosses but opposite sexes are associated with the specific phenotypes

Question 34

life cycle

Answer 34

fruit fly egg hatches into a small larva after 12 hours. the larva is covered with exoskeleton that must shed in order for it to grow: caleld molting. the larva feed into a larger larva. then it forms a pupa, afer 12 horus from emerging from the pupa, the female fly is able to mate and lay eggs again

Question 35

how to differentiarte?

Answer 35

sex combs are only found in male front legs.
the tip of the abdomen in males is rounded and darker black compared to female

Question 36

50/50 vs 3:1

Answer 36

50/50 is sex linked
3:1 is autosoma

Question 37

sperm and egg join to form a ?

Answer 37

zygote: single celled. the zygote then divides into a multicellular embryo

Question 38

a little about sperm

Answer 38

has a head and flagellum. the sperm head has a vesicle caleld acrosome. it contains enzymes that air the sperm in entering the egg by digesting the jelly coat that surrounds the egg.
- behind the sperm head lots of mitochondria topowr the flagellum

Question 39

egg

Answer 39

ovum is surrounded by a jelly coat

Question 40

the only part we can see of fertilization

Answer 40

formation of fertilization envelope from the vitelline layer

Question 41

when sperm reaches the egg, triggering the release of calcium which causes the exocytosis of cortical granules which turn the vitelline layer into a hardened layer called fertilization envelope

Question 42

ionophores carry certain ions across cell membranes

Answer 42

a23187 is an ionophore that carries ca2+ across any membrane from the side with higher concentration to a side with lower concentration

Question 43

cleavafe: rapid mitotic divisions until 7th cleavage division till it produces an embryo called a blastula. filled with blastocoel

Answer 43

blastula develops intog astrula. endoderm mesoderm and exoderm are known as the embryonic germ layers.

Question 44

gastrulation results in the formation of an internal cavity called archenteron which develops in the gut. the opening into this archenteron

Answer 44

the opening into the archenteron is called blastopore which develops into the anus.