30 Questions
What is the primary function of the hypopharynx in insect mouthparts?
Enabling suction and lapping
What is the characteristic of the mouthparts of insects that feed on blood?
Retractable proboscis with stylets
How many fundamental segments do insects have in their body?
3+6
What is the function of the antennae in insects?
To sense touch and smell
What is the term for the area between the compound eyes of an insect?
Vertex
What is the term for the process of feeding on blood in a mosquito?
Piercing and sucking
What is the characteristic of the mouthparts of cockroaches?
Chewing and tearing mouthparts
What is the main function of the cuticle in an insect's body?
To provide structural support and protection
Which of the following is NOT a part of an insect's leg?
Spiracle
What is the main difference between the exocuticle and endocuticle?
One contains chitin and the other does not
What is the purpose of the pleuron-lateral plates in an insect's thorax?
To provide protection for the wings
What is the function of the tracheae in an insect's body?
To transport oxygen to the cells
What is the main difference between the tergum and the notum?
One is dorsal and the other is lateral
What is the purpose of the haemolymph in an insect's body?
To provide nutrients and oxygen to the tissues
What is the primary function of the haemolymph in the circulatory system of the described organism?
To transport nutrients to tissues and wastes to excretory organs
What is the main function of the malpighian tubules in the excretory system?
To filter off urine from body fluids
What is the storage organ for food in the digestive system?
Crop
What is the characteristic of the blood vessels in the open circulatory system?
They are few and open-ended
What is the form in which nitrogenous wastes are excreted in the described organism?
Uric acid
What is the function of the trachea in the described organism?
To transport oxygen and carbon dioxide
What percentage of the body weight is made up of the haemolymph?
20-40%
What is the characteristic of the haemolymph in terms of its colour and consistency?
Clear and colourless
What is the site of exchange between the cells and the blood in the open circulatory system?
Interstitial spaces
What is the term used to describe the process of an insect shedding its exoskeleton?
Ecdysis
What is the term used to describe the stage of an insect's life cycle between molts?
Instar
What is the main feature of an insect's respiratory system that makes it more efficient than diffusion through water or tissues?
Use of tracheal system
What is the function of the tracheoles in an insect's respiratory system?
To facilitate gas exchange
What is the location of the central nervous system in insects?
Ventral
What is unique about the sensory organs in insects?
They possess all senses, including sight and hearing
What happens to the cuticle during the moulting process?
It is broken down and digested
Study Notes
Insect Morphology and Physiology
- Moulting: casting of skin, also known as ecdysis; the form between ecdyses is called an instar; no moulting or growth after adulthood
- Moulting process: dissolving and digesting old cuticle, laying down new cuticle
Nervous System
- Central Nervous System is ventral and consists of ganglia at intervals
- Insects possess all senses (sight, hearing, etc.)
- Many types of sensory organs: eyes, hairs
- Nerve transmission and inhibition in insects
Respiratory System
- Respiration by tracheal system, a series of tubes connected to spiracles on the body
- Tracheoles are the finest tubes of the tracheal system
- Tracheal system involves the diffusion of oxygen directly from the atmosphere into air-filled tubes
- Diffusion is more efficient than through water or tissues (300,000 times more efficient than water, 1,000,000 times more efficient than tissues)
Thorax
- Three sections: pro-, meso-, and metathorax
- Each thoraxic segment bears one pair of legs and one pair of wings on meso- and metathorax
- Pleuron: lateral plates; Tergum: dorsal plates
- Wings are lateral prologations of tergum segment
- Arrangement of veins is important for taxonomy studies
Insect Leg
- Each thoraxic segment bears one pair of legs
- Each leg consists of coxa, trochanter, femur, tibia, and tarsus with a pair of claws
Abdomen
- Usually 10-11 segments
- Only some segments are seen in certain insects
- A pair of spiracles on each segment
- Also bears the reproductive organs
- Spiracles are openings for air gas exchange and cellular respiration
Internal Anatomy
- Integument contains cuticle
- Cuticle: epicuticle (wax+lipoproteins), procuticle (exocuticle+endocuticle; with chitin and polysaccharids)
- Cuticle also has spines and hairs
Functions of Cuticle
- Protects insect from water loss and environment
- Regulates airflow
- Prevents dehydration
External Morphology
- Tagmosis in general body regions
- Insect fundamental segment number: 6, 3, 11
- Head: one pair of compound eyes, simple ocelli, vertex, frons, clypeus, labrum (mouth parts)
- One pair of antennae
Insect Mouthparts
- Upper lid: labrum
- Upper jaws: mandibles
- Lower jaws: maxillae
- Lower lid: labium
- Hypopharynx enables sucking
- Chewing mouthparts: e.g., cockroach
- Piercing and sucking mouthparts: probosics is labium with labella
- Process of blood feeding in a mosquito
Digestive System
- Alimentary canal: foregut, midgut, hindgut
- Crop is used as a food receptacle
- One pair of salivary glands
- Crop is a temporary food storage area
Excretory System
- Excretion by malpighian tubules acting as primitive kidneys
- Nitrogenous wastes excreted as uric acid to conserve water
Circulatory System
- Blood (haemolymph) is a clear fluid containing haemocysts as phagocysts
- Main function of haemolymph is to transport nutrients to tissues and wastes to excretory organs
- Open circulatory system: blood enters and circulates in interstitial spaces
- Exchange of materials between cells and blood is done directly
Test your knowledge of insect external anatomy, including tagmosis, body regions, head structures, and mouthparts. This quiz covers the basics of insect morphology and physiology, including the digestive, excretory, endocrine, and circulatory systems.
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