Osmosis and Diffusion
Why did the tube turn blue in the iodine experiment and why did the iodine stay yellow?
Starch - molecules are too big to diffuse out of the dialysis tubing cell
Iodine - molecules are small enough to diffuse into the dialysis tubing bag, forming a complex with the starch and producing the dark blue colour inside the "cell"
What wavelengths would a plant be most likely to absorb?
A) 450
B) 550
C) 650
450 (blue)
650 (red)
What are the steps of protein synthesis, and what is the difference between these steps?
Transcription - mRNA transcribed from DNA template, in the nucleus
- mRNA editing also occurs to keep the good coding regions (exons) and remove non-coding regions (introns)
Translation - polypeptide chain formed, due to tRNA bringing amino acids to ribosome and matching anticodons with mRNA codons, in the cytoplasm
What are different versions of a specific gene called?
Alleles
Which objective lense do you use when you begin focussing and how close should it be to the stage?
Lowest magnification
All the way up
What happens when you place onion cells into 3.5% NaCl and what is the process called?
Cells shrink - water diffuses out of the cells
Plasmolysis
What is the difference between transmittance and absorbance?
Transmittance - measures amount of light let through the solution
Absorbance - measures amount of light absorbed by molecules in the solution
A and T are inverse of eachother
What are the 3 differences between DNA and RNA, and which nitrogenous bases pair in DNA and which in RNA?
- Thymine, Uracil
- Double stranded, single stranded
- riboneucleic, deoxyribonucleic
DNA: G+C, A+T
RNA: G+C, A+U
What is the difference between dominant and recessive alleles?
Dominant - dominant allele produces dominant phenotype, only needs one dominant copy.
Recessive - recessive allele produces recessive phenotype, needs both copies to be recessive.
What are two things you can adjust to improve the quality of your image?
Fine and coarse focus knobs
Change amount of light
When placed in 3.5% NaCl is the onion cell hyperosmotic or hypoosmotic?
The cell is hypoosmotic and will lose water to the NaCl solution causing the cell to become hypertonic.
What is the purpose of a blank and when should you re-blank?
So the spectrophotometer can use the blank solution's absorbance as a zero reference
Re-blank when changing wavelengths
What direction do DNA polymerases move in when replicating DNA, and what kind of fragments does this create? What are the two strands called that are created?
5' to 3'
Okazaki fragments
Leading and lagging
Parent generation - pure plants
First generation - all hybrids that show the dominant trait
Second generation - 3:1 phenotypic ratio
-Where do you write the figure caption and what to include?
BELOW THE FIGURE
Why does the rate of water influx change with increasing sucrose concentration?
The higher sucrose concentrations have a greater concentration difference to begin with and also retain more water (due to sucrose change).
Why is the absorbance spectrum wider in a leaf than in isolated chlorophyll A?
Leaf - also has accessory pigments to absorb more wavelengths.
What is the difference between a silent and frame shift mutation and how will these impact the protein?
Silent - doesn't affect it
Frame shift - can result in diff. protein, is a deletion or insertion in DNA
What is a transposable element?
DNA sequence that can change its position in the genome
"jumping gene"
What is the magnification when you are looking through the 40x objective lense?
400x
In the experiment where a tube full of 50% sucrose was suspended in water while a tube full of water was suspended in 50% sucrose, why did the rate of water movement differ between the two bags?
50% sucrose tube in water - should GAIN weight more slowly because pressure will cause resistance in the movement of water into the bag
water tube in 50% sucrose - should LOSE weight more quickly
How did DCPIP interact with Photosynthesis and the Electron Transport Chain and what effect did this have on its colour?
- DCPIP takes the place of NADP+, intercepts the electron transport chain and accepts an electron
- Causes the cuvette to become colourless (which increases transmittance)
How does tRNA help to translate an mRNA sequence into a specific protein?
-Transfer RNAs carry amino acids to the ribosome (translation step) to make a protein
- tRNAs have anticodons (triplets of nitrogenous bases) that allow them to bind to the complementary codon on the mRNA
- after getting to the end of the ribosome the tRNA will leave and be used to carry another amino acid
- amino acids are joined via peptide bonds
What is the function of Tb1 and BRC1 and how would they be expressed in a crop planted at high density?
Inhibit branching
High expression (so less branching when closer together)
Are the DNA strands identical? If not, what are they?
No! Antiparallel