L1 and 2 Head

Question 1

Which habitats do insect occur in?

Answer 1

Every terrestrial and freshwater habitat

Question 2

Why are insects a good food source?

Answer 2

most are ~60% protein, higher than steak and soybeans

1900 species known to be edible to humans

Question 3

how can insects have economic impacts

Answer 3

pests- economically damaging

can be valuable eg silk moths, 5500 caterpillars make 1kg silk.

Question 4

What do family names end in?

Answer 4

-idae

Question 5

What does it mean if a name is in brackets?

Answer 5

Described by that person, may be changed

Question 6

What 7 features make insects so successful?

Answer 6

1. evolution of an exoskeleton [less prone to desiccation, more advanced than hydrostatic skeleton]
2. Small size [increases no. niches available]
3. Short generation time [=fast adaptation so very successful]
4. Flexible lifecycle patterns [occupy different habitats and food resources so not in comp with young].
5. Internal fertilisation [ successful in dry environments]
6. flight [more niches, pred. avoidance, movement]
7. complex sensory systems

Question 7

What would the ancestor of insects been like?

Answer 7

Metameric organism [each segment has a pair of jointed appendages]
Tagmatisation: head of 6 segments, Thorax of 3 and abdomen of 11 segments.

Question 8

What are the 6 segments of the head?

Answer 8

1. Labral
2. Antennal [has antennae and ocelli]
3. Post antennal [Has compound eye]
4. Mandibular
5. Maxillary
6. Labial

Question 9

Which head segments have mouthpart elements?

Answer 9

1,4,5,6

Question 10

What organ is at the base of the antennae in the Pedicel?

Answer 10

Johnston’s organ - Stretch receptor

Question 11

What 3 parts of antennae are there?

Answer 11

Scape, pedicel and flagellum [looks segmented, but not true segments]

Question 12

Give 2 examples of different types of antennae

Answer 12

Moths have plumate antennae - males more plumose so can sense female sex pheromones.
Diptera have aristate antennae - arista extends off flagella

Question 13

Describe the ocelli

Answer 13

usually 2 or 3 in a triangle formation. Not present in all insects but are important in flying insects.
Very light sensitive, possible detect the horizon.

Question 14

What are antennae and mouthparts derived from?

Answer 14

A jointed leg

Question 15

Why is saliva important?

Answer 15

Coats food so easy to swallow
Has digestive enzymes
Salivary gland is often modified eg to make silk or venom

Question 16

Describe an insect adapted to a liquid food source

Answer 16

Mosquito, Diptera
Males - nectar, females - blood.
Labium hugely elongated with a U shaped gutter, holds maxillae, amdibles and hypopharynx inside.
Palps - Modified into huge fleshy lobes (labellum), senses host surface to find capillary.
Maxillae and Mandibles - v thin and elongated with cutting structures at the tip used to cut through skin
Hypopharynx - Plunges into hole in capillary. Transports saliva from head to food source

Question 17

Describe mouthparts of a housefly

Answer 17

Lost mandibles
U shaped labium, hypopharynx in centre and salivary canal inside hypopharynx. Labrum across top of U shape. Entire space inside becomes food canal. Labellum v large, has pseudotracheae, uses capillary action to move food across to centre. Sometimes has prestomial teeth.
At rest, mouthparts relaxed and retracted into head.
When feeding, Internal changed in blood pressure extend labium causing labellum at the end to open up.
Saliva pumped down the hypopharynx to digest food source and sucked back up.

Question 18

Describe the mouthparts of a butterfly

Answer 18

Mandibles and labrum hugely reduced
Mouthparts derived from maxillae
Maxillary palps modified into Galea, tubelike, with food canal in centre. Unfurls due to changes in internal blood pressure.
Pharyngeal pump used to suck up nectar.

Question 19

Describe juvenile dragonfly labial mask

Answer 19

Retracts prementum and postmentum into head capsule, changes in blood pressure causes whole mouth structure to shoot forward extremely fast.
At the end of the Prementum there are palpal lobes with hooks.

Question 20

Which mouthparts are the ‘upper’ and ‘lower’ lip?

Answer 20

labrum - upper, mandibled are behind labrum

Labium -lower

Question 21

Which mouthpart attaches the labrum to the head>

Answer 21

Clypeus

Question 22

Describe the segments of maxillae

Answer 22

Cardo attaches to postmentum

Stipes joins to 2 hook like cutting structures (Lacinia an galea) and the maxillary palps, for handling food.