U2T7 - Keywords

Question 1

Division Bryophyta

Answer 1

Simplest group of land plants. 2 main classes - liverworts + mosses. Poorly adapted to live on land, confined to shady, damp places. Mosses anchored in substrate by rhizoids.

Question 2

Rhizoids

Answer 2

Haploid, filamentous outgrowths of gametophyte. No role in water uptake. Don’t deeply penetrate soils + moss distribution limited to areas with water + ions close to soil surface.

Question 3

Division Tracheophyta

Answer 3

Most primitive group to evolve true vascular system, consists of xylem (water + mineral ions) + phloem (organic nutrients). Support by turgor in cells + woody xylem vessel. 2 main groups are pteridophytes + spermatophytes.

Question 4

Diploblastic

Answer 4

Body wall made of 2 cell layers separated by mesogloea. Little differentiation. Outer layer ectoderm, forms epidermis. Inner layer endoderm forms internal structures. Mesogloea separates ectoderm from endoderm.

Question 5

Mesogloea

Answer 5

Jelly-like, non-cellular layer through which cells can migrate. In jellyfish, forms large part of body + acts as hydrostatic skeleton.

Question 6

Polyp

Answer 6

Spends most time attached to substrate (rock). Tubular body, mouth + ring of tentacles on top. e.g. hydra + sea anemones.

Question 7

Medusa

Answer 7

Free swimming bell/saucer shaped individual with tube hanging down in centre. Tube ends in mouth + tentacles line edge of bell. e.g. jellyfish.

Question 8

Nematoblast

Answer 8

Stinging cells.

Question 9

Phylum Annelida

Answer 9

Worm-like animals, clearly segmented aka round worms. Triploblastic. Well developed tissue differentiation. Bilaterally symmetrical + metamerically segmented, long + thin. Hydrostatic skeleton formed from segmental body cavities. Segmentation improves burrowing ability, allowing escape from predators, avoid adverse environmental conditions + exploit new environments. Certain segments may contain specialised structures (repro organs). Have blood system + simple nerve system.

Question 10

Triploblastic

Answer 10

Ectoderm, endoderm + mesoderm.

Question 11

Mesoderm

Answer 11

Contains coelom, within which lies well differentiated digestive + other systems. Forms bulk of body + gives rise to important structures like true muscles.

Question 12

Coelomate

Answer 12

Having a body cavity.

Question 13

Through Gut

Answer 13

Gut with mouth + anus, showing regional specialisation.

Question 14

Phylum Arthropoda

Answer 14

Insects + spiders. Bilateral symmetry, fixed num of metameric segments. Most successful group as vast range of features for any ecological niche. e.g. mouth parts for chewing (locust), proboscis (green fly), large wings for flight, stings to disable prey.

Question 15

Insects (Arthropods)

Answer 15

Have 3 segments in thorax, 10/11 in abdomen. Clearly defined body, thorax + abdomen. 3 pairs of jointed limbs attached to abdomen, through gut w/ mouth + anus. Exoskeleton made of chitin, can limit size but waterproof.

Question 16

Proboscis

Answer 16

Elongated sucking mouthpart that is typically tubular + flexible.

Question 17

Detritivores

Answer 17

Obtain nutrients by consuming decomposing organic matter.

Question 18

Phylum Platyhelminthes

Answer 18

Flatworms. Flat, unsegmented, bilaterally symmetrical, possess well differentiated organ systems, triploblastic, show tissue differentiation but aceolomate, no specialised skeletal system but mesenchyme supports body, most have mouth but no anus. Usually hermaphrodites with complex repro system. Flattened dorso-ventrally.

Question 19

Aceolomate

Answer 19

Have no coelom.

Question 20

Coelom

Answer 20

Body cavity. Fluid filled space where organs are suspended. Blood vessels evolved from mesodermal lining of this + are within it.

Question 21

Mesenchyme

Answer 21

Form of mesoderm.

Question 22

Organ

Answer 22

Made up of diff tissue types which work together to carry out specific role.

Question 23

Flatworms (platyhelminthes)

Answer 23

Have only tube-like gut/enteron so solid tissue fills space between outside + gut. Allows specialisation to occur but many cells per unit vol involved in metabolic activity so high O2 + metabolites demand. Most others have coleom. Organs crammed into body as no coleom so dense + solid. No coleom so no blood vascular system. Have more tissue than cnidarians. Single gut opening.

Question 24

Phylum Chordata

Answer 24

Triploblastic, coelomate animals with mesoderm containing coelom, inside which is well differentiated digestive, reproductive, circulatory + excretory systems. Bilaterally symmetrical + segmented. Internal skeleton + post-anal tail at some stages in life cycle, may be reduced/lost in some species. Have notochord/spinal column. Vertebrates.

Question 25

Notochord

Answer 25

Slender, stiff but flexible dorsal root rod running along back. Originates from mesoderm that runs along back in embryo of all chordates. Persists in primitive chordates.

Question 26

Vertebral Column

Answer 26

In vertebrates, made of cartilage/bone.

Question 27

Cartilaginous Skeleton

Answer 27

In cartilaginous fish, forms strong, rigid + flexible backbone.

Question 28

Spinal Column

Answer 28

In bony fish, amphibians, reptiles, birds + mammals. Skeleton made of bone. Consists of internal jointed system of calcified bone.

Question 29

Chordates Segmentation

Answer 29

Secondary swimming adaptation. S-shaped wiggle characteristic of swimming produced by segmental muscle blocks/myotomes which contract 1 after another in serial pattern.

Question 30

Biological Symmetry

Answer 30

Balanced distribution of body shapes (radial, bilateral, spherical, biradial symmetry + asymmetry)

Question 31

Radially Symmetric

Answer 31

If body of organism can be divided into identical halves in any place. Symmetry around central axis, no left or right.

Question 32

Bilaterally Symmetric

Answer 32

If organism’s body divided by particular plane + resulting left + right sides are mirror image of each other. Generates only 2 sides as left + right.

Question 33

Mosses (bryophytes)

Answer 33

Lack true roots, stems + leaves + don’t possess vascular tissue, support by turgor. Cells organised into structures with superficial similarity to stems + leaves, rhizoids anchor to ground. Water + minerals gained/lost over entire surface. ‘Leaves’ don’t have cuticle/stomata.

Question 34

Vascular Tissue

Answer 34

Xylem + phloem

Question 35

Pteridophytes

Answer 35

Ferns. Have true roots, stems + leaves (subdivided into pinnae) Have vascular tissues in roots, stems + leaves for water, ion + organic nutrient transport. Allows more growth. Support by turgor in cells + lignified xylem. Waterproof cuticle + stomata with fine control in leaves so can colonise drier areas. Rhizome runs horizontally undergrounds with leaves above ground.

Question 36

Spermatophytes (angiosperms)

Answer 36

Flowering Plants. Variable forms, includes herbs + trees. Have true roots, stems + leaves with waterproof cuticle + stomata with fine control. Developed vascular tissue, roots can penetrate deep for water + minerals.

Question 37

Pinnae

Answer 37

Leaflets in ferns.

Question 38

Animals

Answer 38

Eukaryotic, multicellular organisms that don’t have cell wall. Heterotrophs. Most capable of locomotion.

Question 39

Heterotrophs

Answer 39

Feed on organic food that they can digest internally.

Question 40

Metamerically Segmented

Answer 40

Body divided into large num of structurally similar segments, each with own body cavity. Most segments similar in structure with own cavities.

Question 41

Arachnids (arthropods)

Answer 41

4 pairs legs, 2 main body sections (cephalothorax + abdomen)

Question 42

Cephalothorax

Answer 42

Head + thorax of spiders.

Question 43

Segmentation

Answer 43

Linear series of repeating units.

Question 44

Vertebrates

Answer 44

Vertebral/spinal column with segmented muscle blocks, skeleton consists of internal jointed system of calcified bones.

Question 45

Non-vertebrate Chordates

Answer 45

Small group of rare animals. Bridge between invertebrates and vertebrates. Have stiff dorsal rod/notochord instead of true backbone/vertebrate column.