Invertebrates 1
What phylum of animals lacks true tissues and is considered the "basal" group?
Porifera (sponges)
What are the three primary components of the mollusk body plan, and what is the function of the mantle?
Muscular foot, visceral mass, and mantle. The mantle secretes the shell and protects the internal organs.
Explain the functional difference between diploblastic and triploblastic animals.
Diploblastic have two germ layers (ectoderm/endoderm); triploblastic have three (adding mesoderm), allowing for complex muscles and organs
Distinguish between negative and positive feedback loops in biological systems.
Negative feedback returns a variable to a set point to maintain balance; positive feedback amplifies a stimulus away from the set point
A parasite is found in a human intestine. It has no mouth, no digestive tract, and is thought to have been ingested via undercooked meat
Cestode (Tapeworm)
What cell type in sponges generates water currents and filters food particles?
Choanocyte
What is "ecdysis," and why is it a necessary but dangerous process for Ecdysozoans?
It is the molting of an exoskeleton; it is necessary for growth but leaves the animal soft and vulnerable to predators until the new shell hardens.
What are Hox genes, and why are they so highly conserved across different animal species?
They are genes that control the body plan and placement of appendages; they are conserved because they are essential for correct embryonic development.
Compare and contrast the energy costs of endothermy versus ectothermy.
Endothermy is more energetically expensive because it requires metabolic heat; ectothermy is cheaper as it relies on external heat source
In a lab, you remove the amoebocytes from a sponge. What process is most immediately stopped?
Nutrient distribution and spicule formation
What phylum includes jellyfish and corals and is characterized by stinging cnidocytes?
Cnidaria
Describe the physical characteristics of this phlyum
Describe the body of an arthropod (insects)
Body in 3 parts --> Head, thorax, abdomen
Thorax has 3 pairs of legs, 0-2 pairs of wings
Head has 1 pair of antennae, compound eyes, mandibles for chewing/grasping
Abdomen: complex organ system
A sea star is injured and loses an arm. Why can it regrow the arm?
It is a deuterostome with indeterminate cleavage
Distinguish between basal metabolic rate (BMR) and the metabolic rates of smaller versus larger animals.
BMR is the energy used at rest; smaller animals have a significantly higher metabolic rate per gram of body mass than larger ones.
If a mutation occurs in a Hox gene, what is the most likely phenotype of the developing embryo?
Appendages growing in the wrong body segments
Tapeworms absorb nutrients directly from a host's intestine because they lack these two features
Mouth and gastrovascular cavity
Name the organisms that have a closed vs open circulatory system and describe what this means
Open: Arthropoda and Mollusca --> Hemolymph and don't have blood pigments for carrying O2
Closed: Annelida --> Blood and tissue fluid are separate and gas and nutrient exchange is across capillary beds
What are the four main types of animal tissues, and what is one primary function for each?
Epithelial (lining/protection), Connective (support), Muscle (movement), and Nervous (signal transmission).
Compare torpor, hibernation, and estivation as energy conservation strategies
Torpor is short-term; hibernation is a long-term winter adaptation; estivation is summer torpor to survive high heat/water scarcity.
A scientist discovers a new species of Ecdysozoan that is unsegmented, covered in a tough cuticle, and has a psuedocoelem. It is a:
Nematode
How do the feeding strategies of Bivalves differ from those of Cephalopods?
Bivalves are suspension-feeders using ciliated gills to filter food; Cephalopods are active predators using grasping tentacles and beaks
Describe myriapods and the two examples
many identical segments & legs, chewing mandibles for feeding, 1 pair antennae, all terrestrial
Millipedes -detritivores/herbivores --> 2 pairs legs/segment
Centipede – predators – --> 1pair leg/segment with poison claw
Name the 6 characteristics that phylogenies are based on
Analyzing whole genomes, Morphological traits, Ribosomal RNA (rRNA) genes, Hox genes, Protein-coding nuclear genes, Mitochondrial genes
Describe the distinct roles of astrocytes and oligodendrocytes in supporting nervous tissue
Astrocytes regulate the chemical environment of the neuron; oligodendrocytes provide insulation (myelin) for efficient signal transfer
You find an animal with pentaradial symmetry as an adult, but bilateral symmetry as a larva. It uses a water vascular system. This animal is a:
Echinoderm