- The layer of follicle cells that surround the unfertilized egg is called the
- The ________ is formed by the allantois, blood vessels, and yolk sac.
- The process that divides different portions of the zygote's cytoplasm among blastomeres is called __________.embryogenesisfertilizationplacentationcleavage
- During amphimixis,the ovum finishes meiosis II.sperm become haploid.meiosis occurs.the male and female pronuclei fuse.gametes are formed.
- The cell that directly results from the fusion of a secondary oocyte and a single sperm is called a(n)
- After fertilization, the first cell division is completedwithin a few seconds.about 6 hours later.in 12 hours.within the hour.about 30 hours later.
- The period of gestation when organs and organ systems complete most of their development and the fetus looks distinctly human is the ________ trimester.
- The site where fertilization normally occurs is in theunion of the vagina and uterus.uterine wall near the fundus.fimbrae.outer one-third of the uterine tube.cervix.
- Unique features of vertebrates include the presence of a ___. A endoskeleton B notochord C skull and backbone D pharyngeal slit E true coelom
- Which animals have a cylindrical body that is tapered at both ends? A molluscs B annelids C cnidarians D roundworms E platyhelminthes
- ___ are the most diverse group of arthropods. A millipedes B arachnids C crustaceans D insects E centipedes
- Nearly all ___ are aquatic. A centipedes B millipedes C crustaceans D insets E arachnids
- A ___ is an example of a mollusc that does not have a shell. A snail B squid C oyster D octopus E clam
- Which of these exhibits radial symmetry? A) butterfly B) shoe box C) ferris wheel D) automobile E) spoon
- What characteristic is unique to echinoderms? A a lack of segmentation B larvae with bilateral symmetry C suction cup like feet D a water vascular system E a true coelom that forms the digestive tube
- Natural selection can be defined as ___. A) the production of more offspring than can survive in a given environment B) the evolution of a population of organisms C) a process in which organisms with certain inherited traits are more likely to survive and reproduce than individuals with other traits D) a process in which organisms with certain inherited traits are more likely to survive and reproduce than other individuals
- The arthropod skeleton is composed of ___ A salicylic acid B glycogen C peptidoglycogen D cellulose E chitin
- There are more species of ___ than any other type of animal. A annelids B nematodes C molluscs D chordates E arthropods
- How do sponges differ from all other animals? A sponges are autotrophs B sponges lack a true body cavity C sponges exhibit radial symmetry D sponges lack true tissues E sponges have a true coelom
- Which of the following is a characteristic of all chordates? A they all exhibit radial symmetry B they all have a notochord sometime during the life cycle C they all have an endoskeleton sometime during the life cycle D they all have a pseudocoelom E they all have vertebral columns