science exam review! Flashcards
what are 3 things Mendel discovered?
- 2 copies of each gene are in each cell. organisms inherit one gene from mother and one from father.
- there are dominant and recessive traits, sometimes the dominant masks the recessive
3.disproved that traits blend (purple and white do not make light purple)
how did he know he had purebred plants in his garden?
many plants were self pollinated and produced plants with the same traits
explain an experiment he conducted with the white and purple flowers
-he had cross pollinated a purple flower with a white one (parental generation)
-the F1 of offspring had purple flowers (no white)
-then the F2 self pollinated and had mostly purple flowers but a little bit of white
why is one trait lost/hidden in the F1 generation when crossing 2 different purebred plants?
the dominant trait masked the hidden trait in the F1 generation. all offspring were hybrid (1 dominant trait and 1 recessive trait)
how does the hidden trait reappear in F2?
when the hybrid plants self pollinate, a few offspring will have 2 recessive alleles and show the recessive trait. (it can skip a generation)
what is a allele?
forms of genes, each cell has 2 alleles. each gene controls which traits are expressed/can be observed
purebred Dominant:
Purebred recessive:
Hybrid:
TT tall
tt short
Tt tall
what is the ratio/percentage for traits in the F2 generation of Mendals plant exprements?
3 tall and 1 short (75% and 25%)
purebred dominant 1(25%)
hybrid 2: (50%)
purebred recessive: 1 (25%)
can short pea plants be hybrid?
no tall alleles will mask the recessive traits. to have a short pea plants you have to have purebred recessive.
How is this related to our study of DNA?
DNA is made up of genes that code for different traits (alleles)
how is there a probability of inheritance
genes can be in patterns these allow us to predict which traits will be inherited.
punnet squares
It allows us to know which genes will combine and which traits will be expressed and which will be masked.
purple and white plant
genotypes possible: all Pp
phenotypes possible: all purple
homozygous
all the same ex: TT or tt
heterozygous
2 alleles of different types ex: Tt
explain how to organisms can have the same phenotype but different genotypes?
ex: black puppies can look the same (phenotype) but one has Bb trait and the other has BB
Incomplete dominance:
both traits are blended together ex: white and red flowers make a pink
polygenic inheritance:
multiple genes
codominance
both show up at the same time ex: a black and white cow make a spotted cow
multiple alleles:
controlled by 3 or more genes
What’s unusual about the sex cell?
they have 1/2 of the number of body cells since during reproduction they join together
who was darwin?
he published a book (the origins of species)
who was wallace?
he came up with the same idea after darwin had and published a book (drawinism)
who got credit?
darwin because he thought of it first
darwins theory?
the galapagos island had finches and tortises that looked like fossils just changed over time
Dna and evolution?
we could see similar organsims had similar dna
evolutionary tree diversity:
each branch represents a new species and the longer the branch the longer it took before the new species appeared
homologous structures:
they are closely related on the tree
bones are held together by what?
ligaments
bones to muscles?
tendons
smooth and cardiac muscles tire and involuntary?
smooth tires slowly cardiac never tires both are involuntary
types of joints how do they move?
-pivot: rotate (neck)
-hinge: move back and forth (elbow and knee)
-ball and socket: move in a complete circle (hip and shoulder)
-gliding: one bone moves over the other (wrist and ankle)
-immoveable: joints that fused together during infancy
the number of bones:
babies have 300 adults have 206 since they fuse
functions of the skeletal system:
-give body shape and support
-protects organs
-stores minerals
-makes blood cells (marrow)
functions of the skin system:
-forms a protective barrier keeping good things in and bad out
-produces vitamin D
-gathers info about environment
-maintains body temp
-eliminates wastes through sweating
top layer of skin:
layer of dead cells where new ones get pushes up to replace them once they fall
how does skin keep you hot/cold
blood vessels close a little to keep heat in and open a little to let heat out
difference between mechanical and chemical digestion?
chemical: uses saliva in the mouth
Mechanical: breaks it into smaller pieces
~both break down food~
4 chemicals of digestion:
-saliva: mouth
-acid: Stomach
-bile: produced by the liver/gallbladder
-enzymes: produced by pancreas
small and large intestine differences:
small: nutrients are broken down and absorbed
large: absorbs extra water
functions of the circulatory system:
-move blood around the body and deliver nutrients
-move wastes and carbon dioxide to remove body
how does breathing work?
with the diaphragm moving down to the lungs to allow lungs to inflate and moves up to push air out
purpose of the nervous system:
gather info about the environment and react to it
female sex cell:
-largest cell
-contains x chromosome (female)
male sex cell:
-smallest cell
-contains either a X or Y chromosome
where does fertilization occur?
through the fallopian tube during fertilization the sex cells join and becomes a zygote the gets implanted in the uterus
eggs in ovaries:
females are born with all the eggs they will have in their life and they get released during a period.
the outcome of fertilization/period
period-eggs release last day if fertilization doesn’t occur
fertilization- zygote floats down to the fallopian tube
how long is the average period?
28 days although everyone is different
4 main parts of the reproductive system:
ovary,fallopian tube,uterus, vagina
how does the nervous system and the muscular system work together?
neurons sense environment, tell brain how to react, then muscles react to it
