CLASSIFICATION OF LIVING THINGS BIOLOGY QUESTIONS

1. a) i) What is meant by the term binomial nomenclature?

scientific system of naming organisms using the generic(genus) and specific (species)

ii) State briefly the general principles of classification of living organisms

• scientific names must be in Latin or should be Latinised
• family names are formed by adding the suffix “idea” to the stem of the genus e.g the genus Rana becomes Ranaidea
• generic names should be a single unique name

b) State the main characteristics of the five kingdoms of organisms

i. Monera

e.g. bacteria

• unicellular (single-celled)
• prokaryotic (genetic material not surrounded by a membrane)
• cell Wall without cellulose
• lack most organelles
• small in size (microscopic)

ii. Protista(protoctista)

• single-celled(unicellular)
• eukaryotic (most cell organelles present)
• when cell Walls are present have no cellulose
• e.g. protozoa and algae
• usually microscopic

iii. Fungi

• have hyphae (which form mycelia)
• absence of chlorophyll
• have rhizoids (lack roots, leaves, stem)
• have spore forming structures (sporangia)
• e.g. mucor, rhizopus

iv. Plantae

• most are green/contain chlorophyll
• autotrophic/feed by photosynthesis
• cells have cellulose cell walls
• respond slowly to stimuli (tropism)
• lack locomotion (are stationary)
• indefinite growth (at meristems)
• lack specialized excretory structures

v. Animalia

• cells do not have cell walls
• most carry out locomotion
• heterotrophic
• fast response to stimuli (tactic)
• have specialized excretory structures

c) Describe the economic importance of

i. Fungi

• some cause decay to our food
• some cause diseases in humans and animals e. g. ringworms
• may be used as food e. g. mushrooms, yeast
• some are used in the production of antibiotics e. g. penicillin, chloromycetin, streptomycin
• yeast is used in the brewing industry, and baking and source of vitamin B
• many cause diseases to our crops e. g. late blight
• important in recycling nutrients in the soil since they cause the decay of organic matter
• mycorrhizal association in forest development may help in Water intake/absorption
• help in nitrogen fixation

ii. Bacteria

• are useful in the manufacture of antibiotics
• silage formation,
• fermentation of cheese, butter, milk yoghurt
• curing of tea, tobacco and retting flax
• formation of vitamin B12 and K
• enzymes such as amylase and invertase
• hormones such as insulin '
• vinegar, acetic acid, lactic acid, citric acid
• in septic tanks and modern sewage Works make use of bacteria
• biogas production
• saprophytic bacteria are used in compost decomposition or cause decay
• symbiotic bacteria are used in compost decomposition or cause decay
• symbiotic bacteria in herbivores/ruminants help in digestion
• some diseases in animals/humans and plants are caused by bacteria
• many bacteria cause‘ food spoilage/decay
• nitrifying and nitrogen fixing bacteria increase soil fertility/make nitrates available
• denitrifying bacteria reduce soil fertility/convert nitrates into nitrogen/reduce nitrates

d) State the main characteristics of the following division of kingdom plantae

i. Bryophyte

 e.g. mosses and liverworts

•  presence of rhizoids
•  lack of vascular tissues (lack phloem and xylem)
•  body pans not differentiated into root, stem, leaves
•  capsule or seta
•  gametophyte generation dominant.

ii. Pteridophyta

e.g. ferns

• has true roots, stems and leaves
• fond with sori on under-surface
• vascular tissues present
• sporophyte generation is dominant

iii. Spermatophyte

• photosynthetic
• well-differentiated into roots, stems and leaves
• well-developed vascular system
• seed-bearing plants

e) Name sub-divisions of spermatophyte and state the characteristics of each class

i. Gymnospermae (cornifers)

• naked seeds (exposed
• are all woody trees
• reproduce by means of cones
• show xerophytic characteristics
• xylem have tracheids but lack vessels
• phloem lacks companion cells ~
• single fertilization
• pollen lands directly on ovules

ii. Angiospermae (flowering plants)

• reproduce by flowers
• seeds enclosed (in fruits)
• flowers bisexual hence double fertilization
• herbaceous
• pollen grains land on the stigma of the pistil
• xylem contains vessels
• phloem contains companion cells
• ovules contained in the ovary

iii. Name the classes and state characteristics of angiospermae

Dicotyledonae

• two seed leaves
• network venation of leaves
• regularly arranged vascular bundles
• tap root system
• broad leaves
• secondary growth occurs

Monocotyledonae

• one seed leaf
• parallel venation of leaves
• irregularly arranged vascular bundles
• fibrous root system
• narrow leaves
• sheath-like leaf stalk (petiole)
• no secondary growth

iv)State the importance of plants

• balancing carbon IV oxide and oxygen in the atmosphere during photosynthesis and respiration influence water cycle
• reduce soil erosion by binding soil particles together
• useful products e. g. food, medicine, timber, paper, and clothing
• habitat ( e. g. forests and grassland) for animals which may also be tourist attractions that earn money from the sales of products
• aesthetic value/beauty e. g. flowers, shade/shelter, live fences, windbreaks
• Some are harmful e. g. poisons, weeds, injurious (stinging nettles, thorns), water hyacinth

f) i) Give the general characteristics of phylum arthropoda

• jointed appendages
• presence of exoskeleton
• triploblastic and coelomate
• segmented body
• bilateral symmetry (similar halves)

ii. State the characteristics of the following classes of arthropoda

Diplopoda

the millipedes

• two pairs of legs per segment
• many segments
• terrestrial habitat
• body cylindrical and long
• herbivorous
• one pair of antennae

Chilopoda

the centipedes

• one pair of legs per segment
• many segments
• terrestrial habitat
• body long and ventrodorsal flattened
• carnivorous
• last pair of legs pointing backward with poison claws called maxillipedes
• one pair of antennae

Insecta

• three body pans i.e. head thorax, abdomen
• six legs/three pairs of legs
• a pair of compound eyes
• presence of wings
• a pair of antennae

Crustacean

• two body parts
• segmented body
• have pincers (modified legs) to catch prey
• have hard exoskeleton
• a pair of compound eyes

Arachnida

• body divided into two parts( abdomen and cephalothorax)
• simple eyes
• eight legs (four pairs of legs)

iii) State the economic importance of insects

Beneficial effects

• food supply
• important in food chains
• pollinators
• biological control of pests and other organisms
• aesthetic value
• contribute to decomposition e. g. litter feeders like beetles

Harmful effects

• pests
• vectors
• dirt and disease carriers
• injurious e.g. stings and bites

g) i) State the general characteristics of chordate

• notochord
• dorsal slits (pharyngeal cleft during development)
• bilateral symmetry
• triploblastic (three layer body-ectoderm, mesoderm and endoderm)
• clear cut head formation
• multilayered epidermis
• post-anal tail
• closed circulatory system
• segmented muscle blocks(myotomes)
• single pair of gonads

ii)Give the characteristics of the following classes of chordate

Pisces

• presence of fins for locomotion
• two-chambered heart *
• presence of overlapping scales ~
• presence of gills or operculum for gaseous exchange
• presence of lateral line for protection
• streamlined body
• poikilothermic (body temperature varies with that of environment)

Amphibian

• partially live in fresh Water and partially on land
• poikilothermic
• pentadactylous with two pairs of limbs
• webbed feet for locomotion in water
• body streamlined
• heart is three chambered
• moist skin for gaseous exchange

Reptilia

• scales on body
• poikilothermic
• homodont teeth except tortoise and turtle
• all have limbs except snakes
• skin is dry
• oviparous (lay eggs)
• no pinna (external ear)
• three-chambered heart 9crocodile has four chambers)
• skin not glandular
• no mammary glands

Aves

the birds

• homoeothermic (constant body temperature)
• four-chambered heart
• streamlined body for locomotion in air
• skin dry and covered by feathers
• scales on legs
• hollow bones
• oviparous (lay eggs)
• mouths modified into beaks

Mammalian

• hair on the body
• homoeothermic
• viviparous (give birth to live young) eXcept a few
• have mammary glands
• glandular skin e.g. sweat glands, sebaceous glands
• four chambered heart
• pinna (external ear)
• two pairs of pentadactyl limbs
• presence of diaphragm
• have salivary glands