ENTM 10 Midterm 1 Study Guide
1. What are five reasons why we study insects?
a. Give examples explaining each of these reasons.
1. pre-historic roots: ancient civilizations (pictures of them drawing honey from
2. cultural importance: insects in the media (ex: flight of the bumblebee song)
3. agricultural/economic importance: insects influence growth of mass crops
4.Medical / Veterinary Importance: New insecticidal chemistries: the fact that
insects make up over 80% of all study-worthy biomass
→ trillions upon trillions of individual insects, billions of insects per person
Insects provide necessary nutrients to humans. → Provide food (i.e. Honey)
What’s the fifth reason?!
2. What is natural selection?
Natural Selections occurs only when there is Phenotype variation
The process whereby organisms better adapted to their environment tend to survive
and produce more offspring.
1. Individuals of a species do not reproduce equally (a female of one species may lay less
2. Resources are limited (one group may be trying to dominate the resources)
3. Niche (exerts predation pressure on prey depending on how well a species alters the
distribution of resources to benefit them
a. Give three examples of natural selection.
i. Ex 1: Galapagos finches adapted beak size
ii. Ex 2:Insecticide resistance
iii. Ex 3:evolving complexity
3. What is a phenotype?
A phenotype is the physical trait an insect may or may not have.
a. Name different phenotypes.
● Genetic differences (random mutation may cause a beneficial change and it will stay
● Environmental influences (and organism growing up in a certain environment can look
different than one growing up in another environment - spots on butterflies in wet and dry
4. What factors interact to produce/influence phenotypes?
● Random mutation
● Changes in the environment
5. How is novel genetic diversity acquired?
it is achieve through mutations, random mutations. 6. What are some examples of artificial or experimental selection done by humans that
support the role of natural selection in evolution?
→ plants (Broccoli and Cauliflower).
→ Dogs are another example (all started from wolves and now have different
7. What are the five (six?) characteristics of arthropods?
1. Bilateral symmetry
3. Open circulatory system
4. Trachea or gills
5. Multiple body segments (head, thorax, abdomen)
6. Jointed appendages (segments) (feet, etc.)
8. How many pairs of legs on each body segment do centipedes and millipedes have?
Centipedes: One pair of legs per segment ===>never have an even number of pairs
→ Millipedes : two pair of legs per appendage (does millipede have even
number of legs?Yes, but “never have even number of pairs”)’
9. What type of eyes do insects have?
• Compound-multiple lenses
a. What are these eyes good at detecting? → Small Movement, good at sensing
differences. Insects see in mosaic images.
b. What are these eyes composed of?
● Ommatidium - they are able to pick up images and can get mosaic image
c. What is the simple eye in insects called and what does it detect?
• Ocelli - perceives light intensity & is used for navigation too
10. How many legs do insects have? → Three pairs (6 Total)
a. How many legs do spiders have? → Four pairs (8 Total)
11. Name each of the tagmata of an insect. → Head, thorax, abdomen
a. Name each of the body segments of a spider → Cephalothorax, Abdomen
12. What percentage of organisms are insects?
~73% for insects
50-60% and 70% if it includes the Arthropods
13. What are the five reasons for insect success? Explain why each characteristic is
1. Tough exoskeleton-protects them against water loss, predators, and provides the
strength needed for flight 2. Relatively Small Body size- avoid predators, faster and require fewer resources
+greater niche availability.
3. High Reproductive Rate(female is able to lay hundreds of eggs at once, they have
a short development time[ex. one generation in 5 days], they have parthenogenesis
which is asexual reproduction, so no male needed, and insects are adaptable)
4. Metamorphosis (insects have different life stages that can use different habitats or
serve different ecological roles)
5. Wings(fly to escape predators, can relocate, occupy a different niche or migrate to
another location for breeding)
14. What are the important functions of the exoskeleton?
The main functions of an exoskeleton is to protect organisms from an attack. In addition,
it gives physical support to the skeletons and organs, and also retains water.
15. What are the differences between growth and molting, incomplete metamorphosis,
and complete metamorphosis?
● Growing and molting mean that the insect's exoskeleton has gotten too small, so they
shed it and grow a new one.
● Incomplete metamorphosis (hemimetabolous): The insect goes from egg, to nymph, to
adult. The adult looks just like the nymph, except they have wings.
● Complete metamorphosis (holometabolous): The insect goes from egg, to larva, to
pupa, to adult. The adult looks completely different than the larva or pupa. (Caterpillars
a. What are juvenile forms of insects that undergo incomplete metamorphosis
→ Hemimetabolous - Nymph
b. What are juvenile forms of insects that undergo complete metamorphosis
→ Holometabolous - Larva
c. What are the different juvenile stages of complete metamorphosis called?
• Egg→ Larva→ Pupa → Adult
16. What are the three segments of the thorax? → Prothorax, Mesothorax, Metathorax
Mesa Meta= 2 sets of wings
a. Where do the legs originate? → one pair on each segment of the thorax
b. Where do the wings originate? → Meso and Metathorax (No wings on
17. What type of mouthparts do grasshoppers have? → Chewing mouth parts
• They have pinc