Biology Lab Post Test Review
1. The Nature and Process of Science
 How and why do scientists revise their hypotheses and predictions as they gather
additional information?
o Science is a way of understanding natural phenomena using testable
explanations
o Constant search for better explanations of natural phenomena
o A scientifically literate person is observant and curious about everyday
occurrences in the natural world, asks questions, and then seeks answers
through direct investigation or review of trusted resources.
 Our ability to evaluate the quality and credibility of scientific
information on the basis of its source and the methods used to
generate is crucial.
o Science can be thought of as a way of discovering new knowledge.
o The Scientific method: how scientists generally build knowledge
o An observation is any information gathered through at least one of your
senses.
o An inference is an assumption that is based on observations and past
experiences. (reasoning and observation)
 Scientists use inference to form tentative explanations: hypotheses
that are then tested by means of experiments
 Data are collected during experiments but data alone is not
evidence
o Evidence is the product of the interpretation of data, it is the justification
for whether a hypothesis is supported or not.
o Hypothesis: general statement (multiple phenomena) (includes because)
o Prediction: expected outcome (specific)
o Fact: confirmed repeatedly by critical observations
o Theory: collection of hypotheses- powerful explanations for a wide range
of phenomena
o Scientific knowledge is open to question and revision as new ideas
surface, new evidence is gathered, and new technology allows us to look
at the natural world in new ways.
o Disagreements between scientists is a strength
2. Animal Structures and Processes
 How are organ systems interconnected? How does the structure of the nervous
system facilitate an organism’s sensing of and responses to signals in its
environment?
o Living organisms are defined on the basis of what they must do to stay
alive: they must grow, reproduce, sense and respond to stimuli, obtain and
use energy, and maintain homeostasis.
o Homeostasis: a stable internal environment despite changes in the
external environment
o The Nervous system coordinates and controls all of these life functions in
animals
o The Nervous system processes sensory information and controls
responses to internal changes and external stimuli that may result from
interactions with other organisms, changing environmental conditions, or
typical daily activities.
o Humans have a very complex nervous system that includes the brain and
spinal cord and a lot of nerve tissue that connects all of our organ systems.
o The CNS (central nervous system) contains the spinal cord and the brain
o The nerve tissue outside the CNS collects sensory information and
transmitting instructions from the CNS throughout the body: Peripheral
Nervous System (PNS)
o Neurons: specialized cells that the nervous tissue is composed of that
function together to transmit information throughout the body
 Sensory Neurons: receptors of the eyes and skin convey
information throughout the body
 Motor Neurons: control the contraction of skeletal muscle in
response to instructions from the CNS.
o Circulatory: transports substances throughout the body (heart, blood,
blood vessels)
o Digestive: Breaks down food and absorbs nutrients (stomach, small
intestine, liver, anus)
o Respiratory: Exchanges carbon dioxide and oxygen between blood and
air
o Musculoskeletal: Supports and moves the body (skeletal muscles and
bones)
o Reproductive: Produces gametes and offspring (testes, penis, ovaries,
uterus)
o Integumentary: Protects body (skin, hair, nails)
o Jellyfish lack a defined control center (brain) but have nerve nets that are
made of sensory and motor neurons that control their muscles
o Flatworms are much more simple because they have primitive brains made
up of clusters of neurons at the anterior end (head) of the body and large
nerve cords which is a smaller version of PNS.
o Vertebrates have large brains but size and complexity of the brain varies
between vertebrates, which accounts for differences in computational and
processing ability.
o The more folds (which contain nervous tissue) in the brain accounts for
the intellectual advantage mammals have over fish
o Earthworms and Crickets: both are invertebrates with bilateral symmetry,
cephalization (sense organs concentrated at the anterior end), segmented
bodies, and specialized body parts)
 Earthworm: circulatory system is a series of tubes (hearts) that
pump blood through blood vessels and no respiratory system
because oxygen moves directly into the skin (diffusion). The
digestive system moves from mouth to anus and it has many
reproductive structures

Crickets: 3 main body parts like all insects (head, thorax,
abdomen) and 6 legs. Females have longer abdomens (ovipositor)
through which eggs are laid. The spiracles along each side of the
abdomen are the external openings to the internal tracheal system
(respiratory system) The circulatory system is an open system
because it lacks a heart and closed blood vessels for fluid to travel
through.
o Nerve Cell: information to and from the brain- large and spread out
o Read blood cell: oxygen to cells (small and clustered)
o Epithelial (skin) cell: Protects skin from attack (large and not clustered)
o All cells have a cell membrane, cytoplasm, ribosome’s, genetic material
(DNA)
o All of the body systems rely on other systems in order to function. The
circulatory system relies on the respiratory system for oxygen delivery.
The respiratory system relies on the muscular system for inspiration and
expiration. The immune system relies on the circulatory system for
movement of cells that provide immune function. All systems rely on
circulation for nutrients and on the nervous system for regulatory control.
3. The Functions and Responses of Living Systems
 How do drugs affect the pulsation rate?
o Homeostasis: “steady state” is one of the body’s most important
functions- to maintain a stable internal environment when the
external environment changes
o Thermoregulation: steady temperature regardless of surroundings
o Your nervous system, circulatory system, muscular system, ad
intergumentary system are all involved in keeping this steady state.
o As you heat up, your brain activates cooling mechanisms via your
nervous system, the blood vessels of your circulatory system dilate
near your skin to release heat and sweat is produced to cool the body.
o The human urinary system is also an example of homeostasis. If you
are dehydrated your brain sends signals through your nervous system
that increase levels of antidiuretic hormone in your blood. This
hormone signals your kidneys to reabsorb water back into your body
(darker urine color)
o Diuretics (alcohol and coffee) inhibt the release of ADH which causes
excessive urinary water loss because the brain can’t signal the kidneys
to reabsorb water.
o Neurotransmitter: relaying messages to the next neuron
o Inhibitory neurotransmitters: block nerve impulses
o Excitatory neurotransmitters: amplify nerve impulses
o Most substances exert their effects on the nervous system by
stimulating, inhibiting, or mimicking how a neurotransmitter works.
o Stimulants: stimulate the affected portion of the nervous system by
increasing the effect of an excitatory neurotransmitter or blocking the
effect of an inhibitory one.
o Depressants are the opposite: block the action of the excitatory or
increase the action of an inhibitory one
o Narcotics: induce sleep by binding neurotransmitter receptor sites
that normally receive the body’s natural pain-relieving substances
know as endogenous opiates.
o Psychedelic drugs: change a user’s perception of the environment by
increasing the amount of transmitters released in particular areas of
the brain.
o The pulse rate of a worm can be seen easily because the skin is
transparent.
4. Reproduction and Animal Development
 What is the effect of polluted water runoff on sea urchin fertilization success?
o In order for organisms to successfully reproduce sexually, they must
produce gametes (Sperm and Eggs)
o Sea Urchin eggs and sperm are very similar to our own and provide
valuable information
o Meiosis: process that produces gametes necessary for sexual
reproduction. A parent cell divides twice, while the chromosomes
(packages of genes) double only once, to produce four daughter cells
(the gametes) each of which is haploid (contains only half of the
chromosomes of the parent cell)
o When two haploid gametes (egg and sperm cell) combine during
fertilization, the full (diploid) set of chromosomes is restored.
o Sexual reproduction provides a source of genetic variation: each two
haploid gametes fuse to form a unique diploid zygote.
o 46 chromosomes are organized into 23 homologous pairs (one from
the mother and one from the father)
o Homologous chromosomes line up next to each other (two
opportunities to increase the genetic diversity)
o These two opportunities are:
 Independent assortment: homologous pairs can line up on
either side of the plane of cell division- each individual has two
copies of each chromosome (maternal and paternal) and which
goes into each gamete is random
 Before the chromosomes are segregated into daughter cells,
recombination takes place – the maternal chromosome may
exchange some genetic material with the parental chromosome
within a homologous pair which creates chromosomes that are
not exact copies of those in the original parent cell
 The zygote is then formed by a series of rapid cell divisions
without cell growth-cleavages the total volume of the
embryo remains unchanged but the number of cells within
it increases*
o Mitosis: process of cell replication in which the cell doubles its
chromosomes and then separates the two copies into two separate
nuclei
Two daughter cells that are exact copies of the parent cell are
produced
 The function is to form somatic (body) cells, which are
produced during development, growth and cell development.
o Many marine invertebrates (sea urchins) fertilization events and
development occur outside of the body in the external environment
o Human caused disturbance (runoff of pollutants) can endanger
coastal processes like fertilization of sea urchins because it is sensitive
to small changes in surrounding environmental chemicals
5. Human Gametogenesis, Contraception, and Sexually Transmitted Infections
 How do hormonal and barrier contraceptives function to prevent successful
fertilization and/or transmission of sexually transmitted infections (STIs)?
o The Human reproductive system has evolved. The hormoneproducing endocrine system has become very successful at
reproducing through internal fertilization in order to pass on genetic
material (DNA)
o The structures of the male/female reproductive system along with
certain hormones function to produce genetically diverse gametes
(meiosis) and offspring.
o The production of gametes (gametogenesis) takes two forms:
 Spermtagoenesis: takes place in male testes and results in the
production of four sperm from one spermatocyte (each
division of the parent cell is an even distribution which results
in four sperm of the same size)
 Oogenesis: takes place in the female ovaries and results in
production of one egg and three polar bodies from one oocyte.
(each is an uneven division of the parent cell: one large egg
receives most of the volume of the parent cell and the rest goes
to a tiny polar body)
o After ovulation the egg must be fertilized within 24 hours or ill will
disintegrate. Sperm can remain viable in the oviduct for about 72
hours and if one sperm successfully fertilizes the egg, each gamete
contributes half of the new individuals DNA
o The sex of the offspring is determined immediately after fertilization:
female if the sperm carries an X chromosome or male if it carries a Y
chromosome.
o The Zygote travels down the oviduct, dividing by mitosis as it travels
and is implanted into the endometrium within 6 days when it
continues to develop for 9 months until the fetus is ready to surive
independently
o This developmental period is divided into trimesters (3-month
periods)
 1st trimester: “vulnerable period” is when most of the
development of the offspring’s organ systems takes place
 During this period the developing offspring is vulnerable to
teratogenic compounds (drugs or pollutants, alcohol, caffine)

o Knowledge of the human reproductive system has led to
contraceptives: methods of preventing pregnancy and STI’s.
o Only 100% method is abstinence
o Barrier methods of contraception and hormonal methods
o Barrier: physically prevent sperm from reaching the egg (condom)
o Hormonal: rely on knowledge of natural hormone levels during
different phases of the reproductive cycle
o This may be recommended by a doctor for noncontraceptive reasons
as well: birth-control pills are often prescribed to treat ovarian cysts,
irregular periods, intense menstrual cramps
o Some contraceptives (mainly condoms) are effective at preventing
STI transmission
o Bacterial: can be treated with antibiotics
o Viral: cannot be treated with antibiotics ( they replicate within your
cells and are much more difficult to treat)
o MALE
 Scrotum: houses the testes outside of the body because sperm
cannot develop at body temp
 Epididymis: structure sitting on top of the testes where sperm
continues to mature and motile when a specific protein turns
on their swimming tails
 Vas deferens: tube that mature sperm travel through when
they leave the epididymis during ejaculation
 Seminal vesicles: glands that release a fluid high in sugars that
provides energy for the sperm
 Prostate gland: gland that secretes an alkaline fluid that
neutralizes that acidity of the female’s vagina
 Cowpers gland: gland that secretes a slippery fluid that
lubricates the urethra allowing semen to be released more
easily
 Urethra: tube that coveys both sperm and urine out though the
penis
o FEMALE
 Follicle: chamber of the ovary where the egg matures. Egg is
released every 28 days (ovulation) the egg matures in the
follicle two weeks before it is released
 Corpus Iuteum: solid mass formed from the follicle after the
egg is released- emits important hormones
 Fallopian tube: tube the egg travels down after release from
the follicle and where fertilization occurs if the sperm is
present
 Uterus: houses the developing offspring
 Endometrium: blood-rich layer of tissue that lines the uterus
which thickens in response to hormones and this is where the
embryo implants and develops
Cervix: thick ring of muscle that sperates the uterus and the
vagina and holds baby in the uterus
o HORMONES
o Testosterone: stimulates testes to manufacture sperm; tells brain
when enough sperm have been produced and stops the release of
sperm-producing hormones
o GnRH: triggers the release of fertility hormones called gonadorophins
o LH/FSH: tells testes to produce testosterone
o Inhibin: stops the release of sperm-producing hormones
6. Genetics and Heredity
 Did two identical twin sisters inherit the BRCA1 mutation? How do you
know?
o Each chromosome contains one very long DNA strand which bears
thousands of genes (the functional units of DNA)
o Each chromosome is made up of chromatin: which is a combination of
DNA and protein molecules (histones) that help organize the
chromatin and control the expression of its genes
o DNA strands are tightly packaged as chromatin in order to fit
compactly into your cells
o Most of the time, Chromatin exists as a diffuse mass of fibers so that
the cell’s machinery can access different segments of the DNA
depending on which genes need to be expressed (turned on) or
silenced (turned off)
o As cells divide, DNA is copied in a process called replication, and the
chromatin forms compact chromosomes.
o Each chromosome consists of two identical sister chromatids (the
original chromosome and its copy)
o Karyotype: display that is seen if you break open the dividing cell and
arrange the chromosomes into pairs that match in size and pattern on
gene location
o These matching chromosome pairs are called homologous
chromosomes and they carry genes controlling the same heritable
traits located at the same place on the chromosome but the two
homologous chromosomes may carry different versions of the same
gene (Alleles)
o Homozygous for that gene if an offspring has two identical alleles
o Offspring that has two different alleles for a gene is said to be
heterozygous for that gene
o A sperm of egg carries only one allele for each gene because the two
homologous chromosomes are separated during meiosos. When a
haploid sperm fuses with a haploid egg, a unique combination of
alleles (genotype) is expressed as traits (phenotype) in the diploid
individual. Which is why we look similar to our parents and siblings
but not exactly the same.

o Identical twins are developed when the early divisons of a zygote
produce two separate embryos that continue to develop
independently and are genetically identical