CHAPTER 3
REVIEW QUESTIONS
3.1
Single celled organisms without a true nucleus; single circular chromosome of DNA which
controls the cells activities (sometimes also smaller circular pieces of DNA called plasmids
present); ribosomes different to those of eukaryotic organisms; cells wall composed of murein.
3.2
Cocci (spheres); bacilli (rods); spirilla (flagellated, spiral rods); vibrios (comma-shaped).
3.3
A disease-causing organism.
3.4
Different types of bacteria have different forms of respiration (aerobic, anaerobic or a
combination of both) and thus can live in a range of environments displaying large differences
of oxygen availability. Different forms can also gain their nutrition by being heterotrophic,
chemosynthetic or photosynthetic. Some are parasites. Different forms are able to exist at
temperatures intolerable to other organisms.
3.5
Their chlorophyll and the process of photosynthesis is similar to that of plants.
3.6
The Protista is considered to be an artificial taxonomic group since it contains all eukaryotic
organisms other than fungi, plants and animals.
3.7
Most are unicellular or form loose aggregates of cells or colonies; nearly all respire
aerobically; they are found in aquatic and moist terrestrial environments.
3.8
Similarity to the nutrition of other eukaryotic groups: fungus-like, animal-like and plant-like.
3.9
Rhizopoda move by pseudopodia; Zoomastigina are flagellate; Ciliophora move by cilia and
Apicomplexa have no means of locomotion.
3.10
They are all parasites of animals, and many have a complex life cycle using an intermediate
host to transfer them from one primary host to another.
3.11
Algae lack the specialised structures that are characteristic of plants.
3.12
Algae are classified on the basis of their colour which is determined by a number of pigments;
the nature of their stored food reserves and the composition of the cell wall.
3.13
Plankton are small floating organisms of aquatic environments. Phytoplankton are
photosynthetic plankton.
3.14
They are heterotrophic (animal-like) organisms whose cell walls (plant-like) are surrounded
by chitin, which is a carbohydrate typical of animals.
3.15
Zygomycota – sporangium; Ascomycota – ascus; Basidiomycota – bascidium.
3.16
Only the fruiting body of the mushroom is obvious (like the tip of the iceberg). Most of the
mushroom (the feeding hyphae) is below the ground.
3.17
Lichen are not placed in a specific taxonomic group because they are a mutualistic
relationship between two different organisms – an alga and a fungus.
3.18
The cuticle is a waxy layer that limits the amount of water lost from the plant by evaporation.
3.19
Plant cells are surrounded by a wall of cellulose which provides support as well as aiding in
the movement of water through the plant. In some cells the wall is impregnated with
chemicals which provide further strengthening. Each cell contains a large fluid-filled vacuole
which maintains the water balance of the cell and provides a hydrostatic skeleton. In areas of
the plant specialised for photosynthesis, the cells contain chloroplasts.
3.20
They do not have a vascular system and thus substances must pass from cell to cell.
3.21
They have a vascular system with true roots, stem and leaves, allowing them to exploit drier
conditions since their roots can penetrate into the soil, and absorbed water and minerals can
rapidly be transported to other parts of the plant. The sporophyte generation is the dominant
phase and is not dependent on the gametophyte for its nutrient supply.
3.22
The dark spots are spore-producing structures necessary in the life cycle of the fern.
3.23
The female gametophyte is within the ovule and the male gametophyte is the pollen grain.
3.24
The seed is developed from the ovule after fertilisation and contains the young embryo
sporophyte and a nutrient supply surrounded by a protective outer coating.
3.25
Cones.
3.26
Fern fronds develop sporangia, conifers produce cones, and flowering plants have flowers as
their main reproductive structures.
3.27
Pollen is the male gametophyte, a seed is the fertilised ovule which contains an embryo and
nutritive supply enclosed by a hard coat, and a fruit is the development of the ovary enclosing
the seeds.
3.28
Heterotrophic organisms store excess food as glycogen or fat, lack cell walls around their
cells, and exhibit locomotion at some stage in their life cycle. They are multicellular and, apart
from in the sponges, their cells are differentiated into tissues.
3.29
Since animals are heterotrophic they must actively seek out food by either moving their whole
body or parts of their body.
3.30
Radially symmetrical organisms can produce two equal halves when cut through any diameter
in the dorso-ventral plane, whereas there is only one diameter which will produce equal halves
in a bilaterally symmetrical organism.
3.31
Arthropoda. Since it has an independently moving alimentary canal which is separated from
the outer body wall and an exoskeleton it could be Mollusca or Arthropoda. Only the
arthropods have the head, torso and limbs covered by an exoskeleton.
3.32
The cells of the sponge are not organised into tissues or organs, thus can regroup when they
have been separated.
3.33
The Cnidaria are composed of two tissue layers surrounding a gastrovascular cavity with a
single opening fringed with tentacles which have stinging cells (nematocysts) for capturing
prey.
3.34
a.
b.
Platyhelminthes since it is dorso-ventrally flattened, bilaterally symmetrical and has a
moist surface.
Does it have a single body opening? Does it have a body cavity?
3.35
Nematodes are unsegmented and have a pseudocoelom whereas annelids are segmented and
have a true coelom.
3.36
Phylum Arthropoda – jointed exoskeleton.
Class Arachnida – body divided into cephalothorax and abdomen; four pairs of thoracic legs.
3.37
Although echinoderms begin life as bilaterally symmetrical larvae, the adults display
pentameric symmetry. Their external skeleton is composed of calcarious spicules or plates just
beneath the skin. They have a water-vascular system derived from the coelom, from which
tube feet (used in locomotion) protrude from the skeleton.
3.38
At some stage of their life cycle all chordates have an internal dorsal notochord, a hollow
dorsal nerve cord, pharyngeal gill slits, a ventral heart and a post-anal tail.
3.39
The vertebrates are a Sub-Phylum of the chordates which have distinctive features.
3.30
Fish: all have pharyngeal gill slits.
Agnatha
no scales or jaws
Chondrichthyes gill slits open directly to outside
Pisces
gill slits covered by operculum
The adults of all other classes are usually air breathers, have a basic tetrapod body plan and are
distinguished by their body covering.
Amphibia
soft skin
Reptilia
scales
Aves
feathers
Mammalia
hair