chp 7 8 9 Flashcards
why organelle cannot be seen using a light microscope?
- it is very small
- resolution of the microscope isnt high enough
IF BILAYER IS SHOWN MENTION : the two layers of the membrane are very close to each other
differences between an organ and a tissue
an organ has many functions while a tissue has only one
an organ is made up of many types of cells while a tissue is made of only one similar type of cell
structures that are found in animal cells but not in plant cells
flagella
glycogen granules
cilia
describe the function of mitochondria in the movement of sperm cells
the mitochondria provides energy and ATP and that causes the FLAGELLUM to move.
[ in the question they already mentioned that the sperm MOVES so if you say “helps movement/ swimming” it doesnt count as a mark. you must mention what it moves ]
explain the role of the cortical reaction in the process of fertillization in mammles
the cortical vesicles fuse to the cell surface membrane of the egg cell and that hardens the zona pellucida, thus preventing polyspermy
after fertilization, the egg cell divides by mitosis to form a blasocyst. during this process, totipotent cells become pluripotent. describe how a totipotent cell becomes pluripotent.
as the embryo develops, the totipotent cells change into more specialized cells called pluripotent cells by a process called differentiation this is a process where the gene expression is changed, meaning some genes are turned on or off by epigenetic modification such as methylation. proteins will be formed from the switched on genes and they act as regulatory factors that modify the cell and keeps it producing pluripotent cells.
[ the key is to understand the QUESTION. here they are asking how a totipotent cell turns into pluripotent. ask yourself : what is totipotent? how does it differ from pluripotent? the answer is that totipotent can form all types of cells while pluripotent can do the same but cant from the placenta. this means that pluripotent cells are more specialized than totipotent. so looking at the question now, it is asking : how does specialization happen?” ]
when a question asks to calculate how many times larger something is from another thing, what do you divide by?
big over small
what is the differences between the genetic material of an egg cell and a skin cell
- the genetic material is different due to meiosis
- the genetic material is different due to crossing over
-the genetic material is different due to random assortment of chromosomes - the egg is haploid and it undergoes fertilization to form a diploid zygote
[ in this question the main thing that causes these differences is MEIOSIS so it is important to mention. without meiosis there wouldve been no crossing over, random assortment of having of cells. ]
explain how cells in an embryo become specialized after epigenetic modification
active genes are going to be transcribed and they will create proteins which determine/modify cell structure.
[ just always add determine/modify because the markschemes are bipolar ]
describe the events that occur from the time a pollen grain lands on the stigma to the production of a triploid endosperm nucleus and a zygote
the pollen tube nuclei is going to form a path down the style and to the ovary by releasing hydroletic enzymes that digest the style. as the generative nucleus makes its way down, it will divide by meiosis to produce two male nuclei. one nuclei fuses with the females polar nuclei in order to form the triploid endosperm that acts as a source of food and nutrients for the zygote. the second male nuclei will fuse with the female gamete and undergo fertilization, producing the diploid zygote.
ANY question that asks about why somethings are genetically different, what are the three points to ALWAYS mention?
- it is due to meiosis
- due to crossing over of dna
- due to random assortment of chromosomes
when is there a morula?
just before the blastocyst
describe the events that occur after a sperm enters an egg cell, until a zygote in formed
the cortical granules are going to fuse with the cell surface membrane of the egg and they will release their enzymes that will modify the zona pellucida and harden it, preventing polyspermy. after that the two haploid nuclei (sperm and egg) are going to fuse together.
[ LOGIC QUESTION ]
analysis of some mouse egg cells showed that the lipid droplets were located 10nanometers of mitochondria.
suggest why mitochondria were located within 10 nanometers of the lipid droplets
lipids are needed for atp production and respiration. there is small distance between them so the diffusion of lipids to the mitochondria is faster.
when asked to sketch a graph for continuous variation in a population, what would you place on the x axis and the y axis?
x axis : range of phenotype being used (ex: height)
y axis : number of individuals/ frequency
state the function of the nucleolus
it produces ribosomal subunits
state how ribosomes in prokaryotic cells differ from that of eukaryotic cells
prokaryotic : 70s [ smaller ]
eukaryotic ; 80s [ larger ]
in a prokaryotic cell, state the function of the capsule and the flagellum
capsule ; prevents dehydration
flagellum : allows movement and mobility
explain why cells in a morula are genetically identical
because they all come from the same zygote. they undergo mitosis which produces genetically identical daughter cells and also undergo replication during it so each cell will receive an identical copy of the chromosome
a question asks smth like :
suggest why [insert any two structures of the same organelle] look different in this photograph
they are at different stages in growth.
they were viewed at different angles when the cell was cut
describe how a protein is transported from the ribosomes and then secreted by a beta cell
the rough ER packages the protein into vesicles and those vesicles fuse to part of the golgi apparatus to be modified. the golgi apparatus then packages the modified protein into secretory vesicles that will fuse with the cell surface membrane and the protein will exit by exocytosis
