*Question*
Q: Vertebrates have tissues which are organized into organs which in turn are organized into what? Read this paragraph and choose the correct option from the provided answers: 24.4 Subphylum Vertebrata (Vertebra from Latin vertere, to turn). Characterized by separate bones or cartilage blocks firmly joined as a backbone. The backbone supports and protects a dorsal nerve cord. Vertebrates have tissues which are organized into organs which in turn are organized into organ systems. All vertebrates share the following characteristics: - segmentation - a true coelom - bilateral symmetry - cephalization - a backbone - a bony skull - a closed circulatory system - chambered heart - two pairs of jointed appendages - tissues organized into organs Vertebrate Organ Systems: - Nervous System - Circulatory System - Digestive System Respiratory System - Reproductive System - Excretory System Vertebral column: Not present in higher vertebrate adults. (In humans, the gel-like, spongy core of the vertebral column is the only remainder. Ruptured or herniated disc is an injury to this. ) Cranium: Composite structure of bone/cartilage. Two functions: 1. Supports sensory organs of head and 2. Encloses or partially encloses the brain. What evolutionary relationship could we imagine between sessile echinoderms and the higher chordate animals? Paedomorphic (child-form) hypothesis: basically, evolution of sexual reproduction in what had previously been a larval life stage, or the retention of at least one juvenile characteristic into the adult (adult = sexually reproducing) stage. Some scientists believe that this occurred in a proto-chordate animal lineage. Maybe chordates (and vertebrates) arose from sessile (attached) ancestors. Selection in these proto-chordates maybe began to favor more time in the larval stage, as feeding was more successful or mortality lower in this stage. As larvae got bigger physics shows that the cilia become less efficient for locomotion, favoring the undulating motion allowed by a notochord. Is this hypothesis crazy? A similar example of this today is Epemeroptera, the mayfly, which has almost abandoned its adult stage. Its one-year lifespan is mostly larval with just a... Choices: - artificial systems - information systems - maturation systems - organ systems A:
**Answer**
organ systems

*Question*
Q: Colonial organisms were probably one of the first evolutionary steps towards which type of organisms? Read this paragraph and choose the correct option from the provided answers: Colonial organisms were probably one of the first evolutionary steps towards multicellular organisms. Algae of the genus Volvox are an example of the bridge between colonial organisms and multicellular organisms. Each Volvox , shown in Figure above , is a colonial organism. It is made of up to 50,000 photosynthetic flagellate algae that are grouped together into a hollow sphere. Volvox live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Choices: - double cellular - mutated - fetus - multicellular A:
**Answer**
multicellular

*Question*
Q: What are colonies of cells stuck to a surface called? Read this paragraph and choose the correct option from the provided answers: Prokaryotic cells are extremely small and have a variety of shapes. Most have flagella and a cell wall. They have several other cell structures as well. Their DNA exists as large and small loops. Some prokaryotes form biofilms, which are colonies of cells stuck to a surface. Choices: - membranes - cellular coating - membranes - biofilms A:
**Answer**
biofilms

*Question*
Q: What is responsible for the development of antibiotic-resistant strains of bacteria? Read this paragraph and choose the correct option from the provided answers: Mutations in many bacteria that allow them to survive in the presence of antibiotic drugs. The mutations lead to antibiotic-resistant strains of bacteria. Choices: - mosquitoes - flu shots - negative mutations - bacterial mutations A:
**Answer**
bacterial mutations