Midterm Review & Explanations:
Here are some questions, terms that should be familiar, and important concepts and
pieces of information that you should know. The midterm will consist of 25 questions.
The first portion will be lab stations where you will do things like identify bones and use
traits to determine locomotion or group. The rest of the midterm will consist of multiple
choice, fill-in-the-blank, and a couple of short-answer questions. The exam will cover
labs 1-6 only, as you can tell from the material below, so be sure to thoroughly review
the labs and the information provided in them. Have fun over spring break, and see you
all next week!
1) Know the steps of the scientific process.
Step 1 – Make an observation.
Step 2 – Formulate a hypothesis to explain your observation.
Step 3 – Make a prediction that follows from this hypothesis.
Step 4 – Design a test or experiment to falsify your prediction.
Step 5 – Formulate a conclusion.
2) What was Piltdown Man and why was it important? How was the scientific process
used to dispel the hoax of the missing link?
Piltdown Man was an isolated set of fossilized remains found by British archaeologists
in 1912. The remains consisted of an orangutan mandible and a modern human skull. It
was long thought to be the “missing link” in human evolutionary history. Important
because highly publicized and attention given to human evolution, and the length of
time it took to figure out it was a hoax. In 1953, scientists conducted a series of chemical
based tests and determined it was a hoax based on the date their results gave them.
Also, it was stained to make it look older than it really was.
3) Terms for Mendelian genetics: gene, allele, genotype, phenotype, dominant,
recessive
a. Gene: a heredity unit consisting of DNA
b. Allele: different form of a gene
c. Genotype: genetic makeup of an organism
d. Phenotype: physical characteristics of an organism
e. Dominant: genetic trait that is phenotypically expressed in heterozygotes
f. Recessive: genetic trait that is phenotypically expressed in homozygotes
4) What are Mendel’s two laws of inheritance?
Principle of segregation: During the formation of gametes (eggs and sperm), and
for any given trait, each pair of alleles separates so that only one copy is passed on from
each parent.
Principle of Independent Assortment: The chance that an offspring
receives alleles for one trait is independent of the chance that offspring receive alleles for
another trait.
5) Understand how genotype and phenotype are related for dominant and recessive
traits. For example, a person displaying a recessive phenotype has a homozygous
recessive genotype.
Review lab 2.
6) Be able to make crosses using Punnet squares for single- and double-trait crosses
and to give the outcome for the offspring in terms of probability (i.e., offspring have
a 50% chance of being tongue-rolling PTC tasters).
Review lab 2.
7) What are the four forces of evolution?
Mutation is the alteration of an individual’s genetic material. Mutations occur
spontaneously and are a normal part of life. Some mutations are harmful
(deleterious) and others may be advantageous, but most are neutral, and provide
neither harm nor benefit to the organism. Mutation is the only mechanism of
evolution that can bring about novel alleles.
Gene flow is another mechanism of evolution that can increase genetic variation in
populations. Gene flow involves the movement of alleles from one population to
another. It is predicated both on the movement of alleles, or migration, between
populations and the subsequent reproduction of migrants.
Genetic drift occurs when allele frequencies in populations change as a result of
chance, and is enhanced in small populations. One specific form of genetic drift is
termed founder effect, which occurs when a new group is founded by a subset of
a larger group.
Natural selection occurs when some individuals possess a trait that allows them
to produce more offspring than others in a population. If offspring inherit the
advantageous trait, they too will out-compete and out-reproduce organisms lacking
this adaptation. Over time, many individuals will inherit the adaptation and the
advantageous trait will increase in frequency relative to other forms of the trait.
8) Which is the only force of evolution that creates new variation? Mutation.
9) Which force decreases variation within groups but increases variation between
groups? Gene flow.
10) Which force increases variation within groups but decreases variation between
groups? Drift.
11) When natural selection acts strongly against a trait, what is the effect over time
(review what happened with those poor, furless tiger cubs in lab)? Eventually they
die out over time.
12) What is the term for a specific type of genetic drift in which a new group is founded
by a subset of a larger group? Founder effect.
13) Terms for taxonomy: phylogenetics, cladogram, clade, cladistics, outgroup, shared
derived traits, ancestral traits
a. Phylogenetics: the study of evolutionarily relationships between groups of
organisms
b. Cladogram: tree-like diagram showing ancestral relationships between
organisms
c. Clade: a group made up of an organism and it descendants
d. Cladistics: way to classify species into clades
e. Outgroup: group of organisms used a reference group for determining
evolutionary relationships.
f. Shared derived traits: After separation, new traits may arise in the clade.
Sometimes, all of the individuals in a clade will share one or more such
unique traits.
14) Be able to draw a cladogram based on information about shared derived traits, just
like we did in lab. Review lab on how to do this.
15) What are the four tooth classes (remember, the second one is “canine”, not K-9)?
Incisors, canine, premolars, molars.
16) Know how to write out a dental formula, and remember to check if the top and
bottom teeth have the same formula. Humans = 2-1-2-3 on top and bottom. What
about other species we studied?
17) Be able to tell whether a molar is bilophodont, Y-5, or neither. The configuration of
enamel peaks (cusps) and grooves on the chewing surface of the molars in the lower
jaw of all hominoids. “Y-5” indicates 5 cusps with a Y-shaped groove separation
them and the gap of the Y facing towards the cheek. In bilophodont teeth, there are
two “lophs” or side-to- side ridges capped by two cusps each. This pattern is found
only in Old World monkeys.
18) In which group of primates are you likely to see a dental comb, an unfused mandible
and a metopic suture? Prosimians.
19) What is the ladder of progress, and did we see this pattern when we examined amino
acids in the hemoglobin chain for different primate species? The “ladder of
progress” is a long outdated idea, in which species that branched off earlier haven’t
changed. This would be indicated if, for example, the number of differences with
gorillas were about halfway between those for gibbons and those for humans).
20) Are humans more closely related to chimps or gorillas? Does this answer depend
on the traits/data used? Chimps. Yes. Check out this article:
http://www.sciencedaily.com/releases/2009/06/090618084304.htm
21) If you are given a mutation rate (e.g., 1 amino acid change every million years) and
the number of amino acid differences between two species, be able to give the
amount of time since the two species split. Review lab 4, p.42.
22) Osteology terms: axial skeleton, appendicular skeleton, anatomical position, sagittal
plane, coronal plane, transverse plane, superior, inferior, proximal, distal, medial,
lateral
The axial skeleton includes bones of the skull, vertebral column, and rib cage. Generally
speaking, these bones are involved in providing protection to vital organs and
supporting or carrying outer body parts. The appendicular skeleton includes the bones
of the upper and lower limbs and the girdles (shoulder and hip) that attach the limbs to
the central portion of the skeleton. In order to describe the position of one bone (or body
part) in relation to another, it is necessary to use standard terminology with reference to
a standard body position. In the anatomical position, the body is upright with the
arms by the sides and the palms facing forward. There are three main reference planes:
the sagittal (or medial) plane divides the body into more or less symmetrical left
and right halves. The coronal plane divides the body into front and back halves, while
the transverse plane divides the body into horizontal sections. The terms superior
and inferior describe the position of the structures with respect to
transverse planes. For example, the ribs are superior to the pelvis, while the pelvis
is superior to the knee. Likewise, the knee is inferior to the pelvis but superior to
the feet.
The terms proximal and distal are normally used to refer to the relative positions
of bones or portions of bones in the limbs. Proximal refers to the bone or portion of
a bone that is closer to the axial skeleton. Distal refers to the portion of the bone
that is further from the axial skeleton. For example, the humerus is proximal to
the radius, while the radius is distal to the humerus. The proximal end of the
humerus articulates with the scapula to form the shoulder, while the distal end of
the humerus articulates with the ulna and radius to form the elbow joint.
Another set of terms, medial and lateral, refers to the location of a bone or feature
with respect to the sagittal plane. Those bones that are closer to the midline (or
center) of the body are medial. Those farther away from the midline are lateral. For
example, the lateral end of the clavicle (collar bone) articulates with the scapula at
the shoulder joint, while the medial end of the clavicle articulates with the
sternum. The fingers of each hand, in anatomical position, are medial to the
thumbs, while the thumbs are lateral in respect to the fingers.
23) Bones for which you are responsible:
Skull: frontal, parietal, temporal, occipital, zygomatic arch, maxilla, and
mandible
Dentition: incisors, canines, premolars, and molars
Vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (forming the sacrum), and 4
coccygeal (forming the coccyx).
Ribs: 12 pairs
Pelvis (Os coxa): ischium, ilium, pubis
Shoulder: Clavicle, Sternum, Scapula
Arm: Humerus, Radius, and Ulna
Hand and Wrist: Carpals, metacarpals, and phalanges
Leg: Femur, patella, tibia, and fibula
Foot and Ankle: Tarsals, metatarsals, and phalanges
Be able to identify these bones or groups of bones and to discuss their positions
relative to each other (e.g., the tibia is distal to the femur).
24) Be able to distinguish the skeleton of a primate from that of a non-primate and to
give three traits that helped you make your decision (the table on page 52 of your lab
manual has a lot of useful information). Remember to be specific. For example, “eye
orbit” is not a valid reason for calling a specimen a primate, but “enclosed eye orbit”
is.
25) What are some traits that are typical of prosimians?
a. More Primitive; Similar to the earliest primate ancestors.
b. Greater reliance on the sense of smell
c. Elongated snout; Large olfactory bulbs;
d. Small body size.
e. Often lacking some typical primate characteristics.
f. Lack color vision; Lack bony cups around eyes; Claws instead of nails on some
digits.
g. Usual mode of locomotion is vertical clinging and leaping (VCL).
h. Sometimes nocturnal.
i. Tapetum lucidum.
j. Often solitary.
k. Possess a tooth comb.
26) What are the different forms of primate locomotion?
Quadrupedalism, bipedalism, vertical clinging & leaping, brachiation.
27) Be able to determine a primate’s locomotion using two different methods: a) looking
at traits on the skeleton such as limb length, digits, calcaneus length; b) finding the
intermembranal index (you would be given the equation, a calculator, and the ranges
for the different types of locomotion).
If you have any additional questions, don’t hesitate to email me. Good Luck!
