Classification Flashcards
Classification of the Animal Kingdom
The animal kingdom (Kingdom Animalia) is broadly classified into two groups based on the presence or absence of a backbone: Vertebrates and Invertebrates.
Vertebrates (With Backbone)
Vertebrates are animals with a backbone or spinal column and belong to the phylum Chordata. They are further divided into the following classes:
- Mammals:• Warm-blooded, have hair or fur.
• Give birth to live young (mostly) and nurse them with milk.
• Examples: Humans, lions, whales. - Birds:• Warm-blooded, have feathers, and most can fly.
• Lay hard-shelled eggs.
• Examples: Eagles, penguins, sparrows. - Reptiles:• Cold-blooded, have dry, scaly skin.
• Lay soft-shelled eggs on land.
• Examples: Snakes, lizards, turtles. - Amphibians:• Cold-blooded, can live in water and on land.
• Lay eggs in water; undergo metamorphosis.
• Examples: Frogs, salamanders. - Fish:• Cold-blooded, live in water, and have gills.
• Covered with scales and reproduce by laying eggs.
• Examples: Sharks, goldfish, tuna.
Invertebrates (Without Backbone)
Invertebrates make up 95% of all animals and lack a vertebral column. They are grouped into the following major phyla:
- Porifera (Sponges):• Simplest animals; porous body.
• Lack tissues and organs.
• Example: Sea sponge. - Cnidaria:• Have stinging cells (cnidocytes) for defense.
• Radial symmetry.
• Examples: Jellyfish, corals. - Platyhelminthes (Flatworms):• Flat, unsegmented body.
• Mostly parasitic.
• Examples: Tapeworms, planarians. - Nematoda (Roundworms):• Cylindrical, unsegmented body.
• Many are parasitic.
• Examples: Hookworms, Ascaris. - Annelida:• Segmented worms with a true body cavity.
• Examples: Earthworms, leeches. - Mollusca:• Soft-bodied, often with a hard shell.
• Examples: Snails, octopuses, clams. - Arthropoda:• Largest phylum; have exoskeletons and segmented bodies.
• Divided into:
• Crustaceans: Crabs, lobsters.
• Arachnids: Spiders, scorpions.
• Insects: Ants, butterflies.
• Myriapods: Centipedes, millipedes. - Echinodermata:• Spiny-skinned animals; radial symmetry in adults.
• Examples: Starfish, sea urchins.
What are the main differences between warm-blooded and cold-blooded animals?
(Answer: Warm-blooded animals maintain a constant body temperature regardless of the environment (e.g., mammals, birds). Cold-blooded animals depend on the external environment for body temperature regulation (e.g., reptiles, amphibians, fish).
Describe the key role of Arthropods in ecosystems.
(Answer: Arthropods play essential roles as pollinators, decomposers, and a food source for many other animals. Some are also pests or disease vectors.)
Why are amphibians considered a transitional group between aquatic and terrestrial vertebrates?
(Answer: Amphibians can live in both water and on land, with aquatic larvae that undergo metamorphosis into terrestrial adults. They often rely on moist environments for skin respiration.)
Key Characteristics of Animals
- Multicellular, Eukaryotic, Aerobic, Heterotrophic Organisms:
• Multicellular: Made of many cells.
• Eukaryotic: Cells contain a nucleus and organelles.
• Aerobic: Depend on oxygen for survival.
• Heterotrophic: Obtain food by consuming other organisms (unlike autotrophs, which make their own food).
Unique Features for animals
• Lack cell walls (unlike plants, fungi, and algae).
• Mostly motile (can move) at some stage of their life cycle.
• Exhibit specialized tissues for functions like movement (muscles) and impulse transmission (nerves).
List two similarities and two differences between animals and fungi.
Similarities:
• Both are heterotrophic.
• Both perform aerobic respiration.
Differences:
• Animals lack cell walls; fungi have cell walls made of chitin.
• Animals are motile, while fungi are mostly non-motile.
Unique Characteristics of Animals
- Muscle and Nervous Tissue:
• Only animals possess muscle tissue for movement and nervous tissue for communication and control.- Collagen:
• A structural protein unique to animals, providing support and elasticity. - Specialized Intercellular Junctions:
• Found only in animals and critical for maintaining tissue integrity and function. These include:
• Tight Junctions:
• Form a seal between adjacent cells.
• Prevent leakage of molecules between cells.
• Desmosomes:
• Act as anchoring points, providing mechanical strength.
• Gap Junctions:
• Facilitate direct communication by allowing the transfer of ions and molecules between cells.
- Collagen:
Tight Junctions
Functions:
1. Receptor-Mediated Endocytosis: • Control the intake of substances at the apical surface of epithelial cells. 2. Exocytosis: • Regulate the release of substances at the basolateral surface. 3. Barrier Function: • Prevents the passage of materials between cells, maintaining compartmentalization.
Structure:
• Tight junctions are located near the apical side of epithelial cells and create a continuous barrier to regulate the movement of substances.
_______ junctions form a barrier at the apical side of epithelial cells.
Tight junctions
_______ junctions allow the direct transfer of ions and molecules between adjacent cells.
Gap
Which intercellular junction provides mechanical strength by anchoring cells together?
Desmosomes
Tight junctions are primarily involved in:
Preventing the leakage of molecules between cells
Collagen is significant because:
It provides structural support and elasticity.
Why are tight junctions important in epithelial tissue?
Tight junctions create a seal between cells, preventing the movement of molecules and maintaining the integrity of tissue compartments.
Explain the role of desmosomes in tissues.
(Answer: Desmosomes provide mechanical strength by anchoring cells to each other, especially in tissues exposed to stress, like the skin and heart.
How do gap junctions differ from tight junctions?
(Answer: Gap junctions allow direct communication by transferring ions and molecules between cells, while tight junctions create a barrier to prevent leakage.)
Connective Tissues
Connective tissues provide support, bind structures together, and aid in nutrient transport. They are classified into two main types:
- Loose or Dense Connective Tissues:• Loose connective tissue includes tissues like adipose tissue and areolar tissue.
• Dense connective tissue includes tendons (connect muscle to bone) and ligaments (connect bone to bone). - Special Connective Tissues:• Includes blood, bone, and cartilage.
• Formed by specific cells:
• Fibroblasts: Produce connective tissue proper.
• Chondroblasts: Form cartilage.
• Osteoblasts: Form bone.
• Blood: Formed from hematopoietic stem cells in bone marrow.
Reproductive Characteristics in Animals
- Sexual Reproduction:
• Dominates in most animals, with the diploid stage being the primary life stage.
• Fertilization involves:
• A small, haploid, motile sperm.
• A larger, haploid, non-motile egg.
• Produces a diploid zygote.- Developmental Stages:
• Zygote undergoes mitotic divisions to form:
• Blastula: A fluid-filled spherical structure of cells.
• Gastrula: The stage where germ layers develop.
• Development may be:
• Direct: Young directly grow into the adult form.
• Indirect: Involves a larval stage, which is distinct in form and ecology from the adult.
- Developmental Stages:
T/F Fibroblasts form cartilage in connective tissue. (
Answer: False; fibroblasts form connective tissue proper, while chondroblasts form cartilage.)
T/F. Sexual reproduction involves the formation of a haploid zygote.
(Answer: False; the zygote is diploid.)
Direct development skips the larval stage.
True
_______ are cells that form bone in special connective tissue. ()
Answer: Osteoblasts
The _______ stage is a spherical structure of cells filled with fluid during early embryonic development. (
Answer: Blastula)
