IB DP Biology Topic 5: Evolution and biodiversity : 5.4 Cladistics Question Bank HL Paper 1

Ans: C

X, thermatogales and spirochetes are both groups of bacteria that are classified under the domain Bacteria. They are both considered part of the larger group Eubacteria, which encompasses all bacteria except for the Archaea. Eubacteria are characterized by their cell walls, which contain peptidoglycan, and by their ability to carry out aerobic or anaerobic respiration. While Thermatogales and spirochetes have different shapes and structures, they share many of these fundamental characteristics that define the Eubacteria.

Y, Methanogens, extreme halophiles, and thermophiles are all groups of microorganisms that are classified under the domain Archaea. Archaea are distinct from bacteria in that they have unique genetic and biochemical characteristics. For example, the cell walls of Archaea lack peptidoglycan, which is a defining feature of bacterial cell walls. Methanogens are a group of Archaea that produce methane as a byproduct of their metabolism. Extreme halophiles are a group of Archaea that are adapted to living in extremely salty environments. Thermophiles are a group of Archaea that thrive in high-temperature environments. These three groups of Archaea are classified together because they share many genetic and biochemical characteristics that distinguish them from both bacteria and eukaryotes.

Z, animals, fungi, plants, ciliates, and flagellates are all groups of organisms that are classified under the domain Eukarya. Eukaryotes are characterized by their cells, which contain a nucleus and other membrane-bound organelles. This distinguishes them from prokaryotes, such as bacteria, which lack these structures. Animals, fungi, and plants are three of the main kingdoms of eukaryotes, and they are characterized by their different modes of nutrition and reproduction. Ciliates and flagellates are two groups of protists, which are eukaryotic organisms that are not classified as animals, fungi, or plants. Ciliates are characterized by the presence of cilia, which are hair-like structures that they use for movement and feeding. Flagellates are characterized by the presence of one or more flagella, which are whip-like structures that they use for movement. Despite their differences, all of these groups of eukaryotes share many fundamental genetic and biochemical characteristics that distinguish them from prokaryotes.