Download Biology Standards (For the Year) *DO NOT LOSE THIS!* CST

Biology Standards
(For the Year)
*DO NOT LOSE THIS!*
CST Released Questions Practice: http://www.sciencegeek.net/Biology/review/CST.htm
1a) Cells are enclosed in a semi-permeable membrane (phospholipid bilayer) that regulates what
molecules come in & out of the cell. Molecules that move through (only if the cell uses energy)
require active transport. It’s called passive transport if a molecule can pass through with no
energy being used.
1b) Enzymes are proteins that catalyze (speed up) biochemical reactions in cells by lowering the
amount of energy needed to activate (start) the chemical reaction. Enzymes aren’t used up in a
reaction but un-normal temperatures or pH can change enzyme shape, destroying its ability to
work.
1c) Prokaryotes cells are simpler life forms because they don’t have membrane bound organelles
(bacteria, etc.). Eukaryotes are complex cells with many organelles and are typical of more
complex forms of life (animals/plants). Viruses aren’t cells (or alive) b/c they have DNA or RNA
but need a living cell in order to replicate.
1d) DNA’s genetic instructions encode for the nucleotides that are copied (transcribed) into
messenger RNA (mRNA), which is then taken out of the nucleus into the cytoplasm, to find a
ribosome, so it can be translated to assemble amino acids into a chain that codes for a protein.
1e) The Rough Endoplasmic Reticulum is covered in ribosome’s which is why it’s involved in
protein synthesis and sends them to the Golgi Apparatus for modification, packaging into
vesicles, and transportation out of the plasma membrane to be secreted out of the cell and to
another cell.
1f) Photosynthesis converts sunlight energy into chemical energy as glucose. Specialized
organelles called chloroplasts allow this. Within the chloroplast’s stroma, the light-dependent
reactions break up water to create ATP, NADPH, H+, and oxygen gas. Next, the light dependent
reactions (Calvin Cycle) use CO2, ATP, and NADPH + H+ to create sugars.
1g) Mitochondria are called the powerhouse of the cell because during cellular respiration they
break down stored chemical-bond (food) energy into ATP the cell can use.
C6H12O6 + O2  CO2 + H2O + Energy
1h) Macromolecules called polymers are made up of smaller monomers. Proteins are comprised
of amino acids. Lipids are comprised of glycerol and/or fatty acids. DNA/RNA are comprised of
linked nucleotides.
2a) Mutations and sexual reproduction lead to genetic variation. In meiosis, 1 diploid cell divides
two times to make 4 haploid gametes. In males, all 4 become sperm cells, in females only 1 is
large enough to become an egg (the others are polar bodies).
2b) Meiosis is only for sex cell creation in the testis of males or the ovaries of females. Normal
body cells divide by mitosis, which creates 2 identical diploid cells.
2c) During cell divisions in Meiosis, chromosomes segregate (separate) randomly ensuring
genetic variation and that different allele combinations occur in gametes.
2d) New combinations of alleles are created through fertilization when male and female
gametes create a zygote.
2e) ½ of an individual’s DNA comes from the gamete of each parent. The 2 haploid sex cells fuse
to create 1 diploid zygote.
2f) Normal human somatic cells have 46 chromosomes, of which 44 are homologous
chromosomes and 2 are sex chromosomes. So each human gamete has 22 chromosomes for
body traits and 1 sex chromosome (X or Y)
ON A SEPERATE SHEET
OF PAPER: Using your
book for help, explain
each standard IN
YOUR OWN WORDS,
making sure to
emphasize and explain
each of the important
vocabulary words. Use
the boxes below as a
check list.
2g) The possible genetic makeup of a zygote can be predicted using Punnett Squares to
determine possible allele combinations and their probabilities.
3a) A zygote’s phenotype is determined by its genotype, which is established during fertilization.
Dominant alleles (A)can hide the presence of recessive alleles (a) in the phenotype, though they
are still carried within the genotype {and could be passed on to offspring}.
3b) During meiosis alleles undergo independent assortment especially when on separate
chromosomes. This and the crossing over that may occur increase genetic variation within
offspring.
4a) Genes are a set of instructions in the DNA that specify the # and sequence of amino acids to
create a specific protein needed in an organism. DNA is transcribed into mRNA and translated
using a ribosome. Each 3 nucleotides make a codon, to which tRNA brings the anticodon which is
attached to a certain amino acids. The # and order of AA creates that specific protein coded for
in the DNA.
4b) DNA has 4 nucleotides adenine (A), thymine (T), guanine (G), and cytosine (C). Within the
double stranded DNA, A pairs with T and G with C. However, RNA has Uracil (U) instead of T.
Therefore when DNA is transcribed A is paired with U instead.
4c) Mutations occur in DNA when base pairs are incorrectly matched, which can create an
incorrect codon. However, if a nucleotide is inserted or deleted in can change the whole reading
frame and alter every codon (and thus every amino acid) after the mutation (mistake) creating a
nonfunctioning protein.
4d) Every body cell contains a full set of DNA needed to make any protein in the body. However,
each cell only transcribes the parts of the DNA needed to make the proteins it requires.
4e) A protein’s shape determines its use and functions in the body. The shape of a protein
depends of the # and order of the amino acids that make it up. This is why humans with only 20
AA can create so many different proteins.
5a) Nucleic acids are polymers made of monomers called nucleotides. Each nucleotide is made
up of a 5C pentose sugar, a phosphate group, and 1 of 4 nitrogen bases (C,G,A,T, or U). The
phosphate group and pentose sugar make up the outside of the DNA double helix, and the
nitrogen bases bond the 2 strands together.
5b) When DNA is to be copied during replication or parts are transcribed for protein synthesis,
the strands are separated using enzymes and nucleotides are sequenced by pairing
complementary nitrogen bases.
5c) Genetic engineering (biotechnology) allows us to use our understanding of genetics to
further medicine and agriculture (foods).
6a) Biodiversity is the total # of different species in an ecosystem. The more biodiversity in an
area, the more stable the ecosystem is and the more likely the community can survive a major
change.
6b) Changes in climate, water, and other abiotic factors impact the biotic factors and the levels
of biodiversity. However, human activity including pollution and the introduction of non-native
species can impact biodiversity and population size.
6c) Fluctuations in population size are impacted by competing factors like birth and immigration
that increase its size and by death or immigration that reduce its size.
6d) Photosynthesis in plants and cellular respiration in animals help to counter-act each other
and balance out the location of water, carbon, and oxygen in the biogeochemical cycles.
6e) Producers are extremely important because only they can create chemical food energy out
of abiotic factors (usually sunlight during photosynthesis). They form the beginning of food web
and thusly affect all consumers as well. Decomposers are important because they return raw
nutrients to the soil that are needed by producers.
6f) At each step of the food web (or pyramid) energy is stored within the bodies of the
organisms. However, most of this energy is lost to unusable forms into the environment (up to
90%) as heat.
7a) Natural selection acts on phenotype not genotype. Each organism is affected by its specific
alleles, but can still create progeny with slightly different adaptations.
7b) Some alleles may be lethal in a homozygous individual, while non-lethal in a heterozygous
one. In this case, the heterozygous may survive and reproduce the bad allele to its offspring.
This is why fatal genetic conditions can persist within a gene pool.
7c) New mutations are constantly being generated within a gene pool. These changes to the
DNA can be beneficial, harmful, or make no difference to the survival of the individual,
depending on the conditions.
7d) Variation within a species increases the likelihood that at least some members of a species
will survive under changing environmental conditions.
8a) Evolution is the result of genetic changes that occur in constantly changing environments.
Natural selection determines which individuals survive to pass on their genes through sexual
reproduction. This influences the genotypes and thus the phenotypes of the gene pool and
changes species over long periods of time.
8b) By having higher biodiversity and a great amount of diversity (variations) within a species it
increases the chances that at least some organisms can survive changes in an environment.
8c) Genetic drift through the Bottleneck Effect or the Founder Effect decreases the size of a gene
pool and its diversity. This can decrease the chances of survival of the species.
8d) Speciation can occur due to reproductive isolation or geographic isolation.
8e) Analysis of the fossil record can show us how organisms have adapted, speciated, or gone
extinct in the past. It also gives us clues to the abiotic environmental circumstances of the
ecosystems on Earth during different time periods.
9a) The coordination of organ systems keep the internal conditions of the body relatively stable
(homeostatic) despite changes in the outside environment.
9b + 9e) The nervous system mediates communication between the environment and different
parts of the body. Neurons communicate through chemical and electrical signals. Sense
receptors (in the PNS) detect changes in the environment and relay impulses to interneurons in
the brain and/or spine (CNS) which then signals motor neurons (in the PNS) to create a change in
behavior.
9c) The endocrine system can work with the nervous system. However, it communicates with
the cells in the body using hormones (enzyme chemical signals) released into the blood. This can
create negative or positive feedback loops to regulate body conditions.
9d) The electrical impulse that travels down the axon of a neuron is created by NA+ and K+ ion
concentrations until it reaches the neuron terminal and creates a chemical to cross the synapse
to the next neuron.
10a) Organisms combat disease with the immune system. The 1st step of defense is the skin
which keeps out infectious antigens like bacteria & viruses.
10b) Cells fight antigens by recognizing foreign protein receptors and creating antibodies to
inactivate pathogens directly, or signal immune cells to attack.
10c) Vaccinations use weakened or killed pathogens to allow the antigens to be recognized
without getting the person sick. That way the body will already have antibodies ready if the
person ever encounters that pathogen in real life.
10d) A virus isn’t alive because it has no ribosome’s and harms cells by forcing them to replicate
the viral DNA/RNA until the cell bursts and the viruses spread. Antiseptics can be used outside
of the body to deactivate viruses or bacteria. Bacteria are alive and can be treated using
antibiotics that destroy them or inhibit their growth.
10e) An individual with a compromised immune system (like an individual with HIV) may be
unable to survive to fight off infections caused by even less harmful microorganisms.