2 . G11 LifeSciences DigitalSupport web Diversity Change and Continuity

Study & Master Support Pack | Grade 11 CAPS Life Sciences Diversity, change and continuity This support pack for the Diversity, change and continuity strand of the Life Sciences Grade 11 CAPS curriculum provides revision summaries on the topic to help prepare for the examinations. Learners can work through these individually at home or these could form the basis of a catch-up class or online lesson. You have permission to print or photocopy this document or distribute it electronically via email or WhatsApp. Cambridge University Press Africa is a proudly South African publisher. For more information on our Study & Master CAPS-approved textbooks and valuable resource materials, visit www.cambridge.org Brighter thinking | Better learning www.cambridge.org

UNIT 1: Biodiversity and classification of micro-organisms protista fungi bacteria immune responses of viruses plants and animals to Effects and management of micro-organisms diseases caused by micro- organisms vaccinations Roles in maintaining balance in environment and web of life Immunity antibiotics E. coli in human intestine Biodiversity and Use of drugs Symbiotic relationships micro-organisms effect on nitrogen-fixing micro-organisms bacteria in plants Biodiversity Use of micro-organisms to produce medicines Traditional technology micro-organisms antibiotics insulin viruses fungi producing, e.g. beer, wine, cheese bacteria protista

UNIT 1 Biodiversity and classification of micro- organisms The structure and characteristics of micro-organisms • The basic structure and general characteristics of micro-organisms: Viruses Bacteria Protista Fungi General structure DNA or RNA strand Cell envelope Cell wall, vacuole, Sporangium, aerial surrounded by protein (peptidoglycan), chloroplasts in some, hyphae, mycelium made coat glycocalyx, cell pyrenoid, nucleus up of cells membrane, cytosol, ribosomes, nucleoid Size Very small – electron Microscopic Microscopic – some Microscopic but many microscope only macroscopic examples macroscopic examples Prokaryote or eukaryote Not applicable Prokaryote Eukaryote Eukaryote Unicellular or Not cells Unicellular Unicellular or Multicellular multicellular multicellular Specialised tissue No No No Simple tissue present differentiation Reproduction Only in host cell Asexually by budding Asexually by cell Asexually through and binary fission division, sexual spores, sexually through reproduction in poor cytoplasmic fusion conditions Feeding Not applicable Usually heterotrophs, Autotrophs and Autotrophs, also saprophytic heterotrophs heterotrophs, saprophytic Environment All around but inactive Found everywhere, Moist environments, Moist environments outside host cell can form endospores some can encyst to to resist poor resist drought environmental conditions A envelope B nucleic acid capsid nucleocapsid nucleocapsid Figure 1 Generalised structure of viruses. A An enveloped virus B A naked virus glycocalyx fimbriae chromatin body cell membrane cell wall pilus ribosomes mesosome granule flagellum Figure 2 A rod-shaped bacterial cell

Amoeba (× 75) Chlamydomonas (× 750) cytoplasm contractile vacuole used for osmoregulation pseudopods used for movement food particle contractile vacuole flagellum used being ingested in movement by pseudopods (phagocytosis) cell wall food vacuole nucleus nucleus cell surface membrane cytoplasm vacuoles direction of movement pyrenoid cup-shaped chloroplast Paramecium (× 150) Vorticella (× 100) Euglena (× 250) cilia beat and cause organism anterior end to rotate as it swims along cilia flagellum nucleus stigma (eye spot) food vacuole reservoir contractile cytoplasm vacuole stalk chloroplasts nucleus mouth region where contractile vacuole food vacuole food vacuole forms cell wall posterior end Figure 3 Some examples of different unicellular protista young sporangium containing asexual mature spores sporangium releasing spores stolon which spreads aerial the fungus hyphae mycelium feeding enzymes hyphae released into the bread digesting absorption of digested nutrients nutrients Figure 4 The structure of bread mould (Rhizopus stolonifer) The role of micro-organisms • Bacteria and fungi are major decomposers and recyclers in the environment. They break down dead matter using enzymes, use some nutrients themselves and recycle the rest back into the environment. Symbiotic relationships • Nitrogen-fixing bacteria form symbiotic relationships with plants in root nodules and make ammonia from free nitrogen, which is broken down into amino acids and used to synthesise proteins by the plants. There are also free-living nitrogen-fixing bacteria, which use atmospheric nitrogen to form nitrates.

Micro-organisms and disease • Viruses, bacteria, protista and fungi cause diseases in plants and animals. • Examples of these diseases are: • viruses: rabies, HIV and influenza • bacteria: cholera, tuberculosis and anthrax • protista: malaria • fungi: rusts, thrush, ringworm and athlete’s foot. Types of defence mechanisms • The body’s defence system is made up of the non-specific defence system and the specific defence system. • The non-specific defence system is made up of barriers, e.g. the skin and the mucous membranes of the respiratory, urinary and digestive tracts. Chemical barriers are secretions from the sebaceous glands, tears, hydrochloric acid, perspiration, semen, lysozymes and interferon. • The non-specific defence system includes macrophages, which use phagocytosis, and inflammation. • The specific defence system is the immune system. • Specific immunity provides protection against specific pathogens and their toxins. • This type of immunity is provided by white blood cells called lymphocytes. The two main types are B-lymphocytes (B-cells) and T-lymphocytes (T-cells). • Specific immunity is an acquired response, which allows the body to detect and destroy particular substances. • This type of immunity responds to chemicals called antigens. Each pathogen stimulates the production of a specific antigen. • Antigens activate the immune response and interact with cells of the immune system. Once the body has responded to an antigen, it “remembers” the pathogen. • The next time the body encounters that pathogen or foreign substance, there is a fast, specific secondary response to the pathogen. • This specific defence is carried out by the lymphatic system, which involves the production of two kinds of immunity: cell-mediated immunity and antibody-mediated immunity. • Cell-mediated immunity is carried out by T-cells. • Antibody-mediated immunity is a function of B-cells. The B-cells are responsible for the production of antibodies. • Plants have passive immunity against invaders, provided by physical and chemical barriers. • A vaccine is something that is usually injected into the body to improve immunity to a particular disease. Not all vaccines are injected. • A vaccine usually contains a weakened or killed form of a micro-organism or the toxins produced by a micro-organism. • This stimulates the body’s immune system so that it produces antibodies against a particular disease without making the person ill. • Drugs that are used against micro-organisms are called antimicrobial drugs. These include antiviral drugs and antibiotics, which are effective against bacteria, protista and fungi. Using micro-organisms to produce medicines • Micro-organisms can be used to make antibacterial drugs and also to synthesise insulin. Traditional biotechnology • Traditional technologies for making beer, wine and cheese use processes such as fermentation and souring of milk, which requires micro-organisms.

UNIT 2: Biodiversity of plants advantages and adaptations of flowers sexual disadvantages of each for pollination different pollinators Flowers as reproductive Reproduction in plants structures asexual differences and similarities Biodiversity of plants vascular tissue endemic species in (xylem and South Africa phloem) Grouping of bryophytes, pteridophytes, gymnosperms Significance of seeds and angiosperms seeds as leaves and roots fruit seed banks food source seeds and spores

UNIT 2 Biodiversity of plants The major plant groups • Plants are grouped into bryophytes, pteridophytes, gymnosperms and angiosperms. • These plant divisions are grouped according to the presence or absence of vascular tissue (xylem and phloem), true leaves and roots, seeds and spores, and fruit. Bryophytes Pteridophytes Gymnosperms Angiosperms Vascular No Yes Yes Yes tissue True leaves No Yes Yes Yes and roots Seeds and Spores Spores Seeds and Seeds and spores spores (pollen) spores (pollen) Fruit No No No Yes capsule operculum sporophyte seta foot female rosette male rosette gametophyte "leaf" "stem" rhizoid Figure 1 The structure of a bryophyte, showing the sporophyte and the gametophyte pinnae frond rachis pinnules petiole young frond leaf scales rhizome adventitious roots Figure 2 The structure of a fern

A B C Figure 3 Examples of gymnosperms. A Podocarpus (Yellowwood); B Welwitschia mirabilis; C Widdringtonia (Clanwilliam Cedar) flower terminal bud leaf axillary bud internode node stem root Figure 4 An angiosperm plant showing a flower on a mature sporophyte

Decreasing dependence on water for reproduction There is a decreasing dependence on water for reproduction from bryophytes to angiosperms: • Bryophytes – not yet truly suited/evolved for a terrestrial environment because: • no cuticle, support and strengthening tissue, neither vascular or conducting tissue, thus dominant gametophyte essentially tiny to reduce desiccation • sporophyte totally dependent on gametophyte for support and food • sperm totally dependant on a film of water (dew) to swim to egg. • Pteridophytes – more evolved than bryophytes but still not totally terrestrial because: • leaves have cuticle to protect them from desiccation • vascular tissue to conduct water and minerals (xylem) and food (phloem), but • still dependent on moist conditions for gamete transfer. • Spermatophytes – evolved for a true terrestrial environment: • have all of above terrestrial adaptations, plus • embryo now protected from desiccation by being enclosed in a seed • pollen grains to protect potential sperm from drying out. Asexual and sexual reproduction • Plants reproduce asexually and sexually. There are advantages and disadvantages to each form of reproduction. Flowers as reproductive structures • Flowers are the reproductive structures of angiosperms. • In angiosperms, pollination is required for reproduction. • Different plants have flowers that either self-pollinate, or cross-pollinate using wind pollination, insect pollination and bird pollination. The significance of seeds • Seeds are one of the reasons that the spermatophytes are the most successful plants on Earth. • Seeds can be used as food as well as a means to grow food crops. • Seed banks are established by governments and other agencies to store seeds of different crop varieties and wild plants to make sure that there is plant biodiversity.

UNIT 3: Biodiversity of animals Annelida Arthropoda symmetry and number of tissue cephalisation layers developed from embryo Platyhelminthes Chordata number of Key features in respect openings in gut Cnidaria Six major phyla of body plans coelom and Porifera blood systems body plans and Biodiversity modes of living: similarities and of animals differences Role of invertebrates in soil aeration Phyla agriculture and ecosystems concept of a phylum body plans and grouping decomposition animals in phyla pollination

UNIT 3 Biodiversity of animals The concept of a phylum • A phylum is the taxonomic rank below kingdom and above class. • A phylum can be defined in two ways: • It is a group of organisms that have a similar body plan. • It is also a group of organisms that are related through evolution. Body plans: how these relate to modes of life • There are five aspects of any animal body plan that are important and common to all living animals: • symmetry (asymmetry, radial symmetry or bilateral symmetry) • cephalisation • number of tissue layers developing from the embryo – two (diploblastic) or three (triploblastic) • presence or absence of a coelom (a cavity within the mesoderm) • presence or absence of a through gut. Six major phyla • Phylum Porifera: the sponges – are asymmetrical and diploblastic, and they do not have a coelom or a gut. A Section through a simple sponge B Detail of body wall osculum amoeboid cell collar cells spicule outer dermal layer water and food enter through pore pore cell central cavity spicule secreting cell mesenchyme secretes skeleton Figure 1 A section through a simple sponge Figure 2 The shape of sponges and their skeletons

• Phylum Cnidaria: jellyfish, bluebottles, corals and sea anemones – are radially symmetrical, acoelomate and diploblastic, and have a blind-ending gut. Figure 3 Portuguese man-of-war A Polyp B Medusa mouth ectoderm mesogloea jelly-like endoderm mouth central cavity (coelenteron) tentacle Figure 4 Cnidarian body plans • Phylum Platyhelminthes: flatworms – are bilaterally symmetrical, show cephalisation, are triploblastic, and have a coelom. Anterior end head eyespot sensory lobe digestive cavity in cross section mouth mouth pharynx pharynx opening of opening of pharynx pharynx Posterior end tail Figure 5 A planarian

• Phylum Annelida: segmented worms – show metameric segmentation, are bilaterally symmetrical, show cephalisation, are triploblastic, and have a coelom. segmented body clitellum mouth anus 1 cm Figure 6 The external features of the earthworm, a common annelid • Phylum Arthropoda: insects, chelicerates, crustaceans, myriapods – have many jointed legs, segmented bodies, chitinous exoskeletons and waterproof cuticles. • Arthropods are bilaterally symmetrical, show cephalisation, are triploblastic, and have a coelom. • They are the largest and most successful phylum on Earth. E F A C B D Figure 7 A range of different arthropods: A crayfish; B baboon spider; C mosquito; D African monarch (butterfly); E locust; F centipede • Phylum Chordata: fish, amphibians, birds, reptiles and mammals – are bilaterally symmetrical, show cephalisation, are triploblastic, and have a coelom. • All chordates have a notochord, which is a long rod of supportive tissue derived from the dorsal wall of the gut in the embryo. • Other features that chordates share, although some may be present only in the embryo, are: • a dorsal nerve cord, or spinal cord • bilateral symmetry • gill slits • a post-anal tail • blood that circulates from a main ventral vessel and back through the body in a dorsal vessel. • Vertebrates are the only animals that have a true head that contains a true brain, which is divided into several vesicles that control and coordinate the nervous responses of the body. • The bony cranium is also unique to vertebrates, as is the concentration of sense organs – the eyes, ears and nose – on the head.

Table 1 The relationship between body plan and mode of living in six phyla Symmetry and Tissue layers Number of Coelom and Mode of cephalisation openings in blood systems living the gut Porifera Asymmetrical, Endoderm No gut Acoelomate, no Aquatic – no and ectoderm, blood system mainly marine, cephalisation diploblastic sessile Cnidaria Radially Endoderm Blind-ending Acoelomate, no Aquatic symmetrical, no and ectoderm, gut blood system (marine, few cephalisation diploblastic freshwater), mobile Platyhelminthes Bilaterally Endoderm, Blind-ending Acoelomate, no Aquatic, symmetrical, mesoderm, gut blood system free-living and cephalisation ectoderm, parasitic triploblastic Annelids Bilaterally Endoderm, Through gut Coelomate with Mainly symmetrical, mesoderm, blood vessels terrestrial, some cephalisation ectoderm, throughout marine, highly triploblastic length of body mobile, moist environments Arthropods Bilaterally Endoderm, Through gut Coelomate with Ubiquitous – symmetrical, mesoderm, blood vessels largest phylum, cephalisation ectoderm, terrestrial, triploblastic marine and freshwater, harsh, dry environments Chordates Bilaterally Endoderm, Through gut Coelomate with Ubiquitous symmetrical, mesoderm, blood vessels – terrestrial, ectoderm, and heart, marine, lungs and gills freshwater, aerial, harsh, dry, extreme environments (hot and cold)