Biology Exam

Biology Exam: Short-Note Bilateral Symmetry Anterior (หัว) Posterior (ท้าย) Dorsal (หลัง) Ventral (หน้า หรือ ท้อง) Lateral (ข้าง ซ้าย หรือ ขวา)

Animals (Animalia) • General Characteristics o Multicellular o Eukaryotic cells (no cell walls) o Heterotrophic (non-photosynthetic) o Nervous Coordination (except sponge) • Animal Symmetry o Bilateral symmetry o Radially symmetrical o Asymmetrical

Bilateral Symmetry

Radially Symmetrical

ร่างกายแบ่งครึ่งแล้ว

ร่างกายแบ่งครึ่งแล้ว

เหมือนกันได้แค่เส้นเดียว

เหมือนกันได้หลายเส้น

*Motile creature = can move *Sessile = permanently fixed *Sedentary = slow-moving

Asymmetrical

แบ่งไม่ได้เลย

Animalia

Cnidaria

Mollusca

Nematoda

Platyhelminthes

Annelida

Arthropoda

Echinodermata

The only vertebrate

Cnidarians (Examples: Jellyfish, sea anemones, corals, hydras) • General Characteristics o o o o o o

Diploblastic (two cell layers [endo/ecto –derm] separated by mesogloea) Nematoblasts (stinging cells) Radially symmetrical Tentacles Most are marine Simple body plan (No special respiratory, circulatory, excretory systems  Uses diffusion)

• Cnidarians body plan o

Can exist as 2 forms (polymorphism)  Polyp – เป็น ‘ต้น’ ยึดอยู่กับหิน มีท่อปล่อย medusa – asexually produces medusa  Medusa – เป็น ‘ตัว’ ว่ายน้าได้ คล้ายแมงกะพรุน – sexual state

o

Body wall encloses a mouth (no anus!)

Chordata

• Coordination in cnidarians o o o

Tissue level of organization Nematoblasts occur in the ectoderm of tentacles Simple nerve net coordinates movement (connected to muscle fibrils)

Platyhelminths (flatworms) • General Characteristics o o o o o o

Flat, unsegmented, bilaterally symmetrical Triploblastic (3 layers : endo/ecto/meso –derm) Organ level of organization (including other animals except sponges and cnidarians) One body cavity (gut/enteron) Acoelomate (no coelom – place where organs suspend) 1. Ascaris– intestinal human parasite Diffusion (respiration) 2. Filarial worms– elephantitis (lymphatic) Ectoderm

3. Pinworm – large intestine parasite

Gut or enteron Mesoderm in where gonads and excretory organs can develop Endoderm

• Free-living flatworms o o

Turbellaria (class)  Ciliated outer surface Planaria (genus)  Carnivorous (found in freshwaters)  Simple brain (nerve clusters  nerve organs  nervous system)  Hermaphrodite (2-in-1-sex), but can also reproduce asexually by splitting into 2 or cross fertilization

• Parasitic flatworms o

o

Trematoda (flukes class)  Endoparasites  No cilia on outer surfaces  Possess suckers  Have enteron  Primary and secondary host (sexually mature/sexually immature) Cestoda (tapeworms class)  Endoparasites  No gut cavity  No cilia (enlonged body)  Proglottids (sexually reproducing sections divided)  Possess hooks/suckers (@scolex = anterior end)

• Adaptation of parasitic flatworms o o o o o

Reduced or absent locomotory structures Have ‘anchoring’ structures (hooks, suckers) Lost organ systems and functions that they no longer need [parasitic degeneration] High reproductive output Special way of getting host and defence from host

Annelida (segmented worms) (Examples: Leeches, earthworms, ragworms) • General Characteristics o o o o

Worm-like that are clearly segmented Triploblastic, bilaterally symmetrical Second body cavity (coelom) Mouth+Anus

• Segmentation o o

Ringed body = metameric segmentation Fixed number of segments at all age

• Coelom o o o

Provide space for growing of internal organs Contains fluids which can act as hydrostatic skeleton Allows organs to move independently

• Gaseous exchange in earthworms o o o

Large number of looped blood capillaries Diffusion Pseudoheart

Arthropods (largest phylum!) • General Characteristics o o o o

Triploblastic coelomates Metamerically segmented, bilaterally symmetrical Each segment has a pair of jointed appendages Exoskeleton

• Exoskeleton o o o o

Adopt many different types of locomotion (burrowing, swimming, running, walking, jump, fly) Flexibility and toughness Can be transparent in places (providing camouflage) *Its weight to strength ratio decreases according to size of animal! When it comes to shedding, the body is soft and vulnerable

• Classes o

o

o

o

o

Crustacea (examples: woodlice, crayfish, crabs, lobsters, barnacles)  Aquatic/Damp habitat  Head not distinct from thorax (caphalotorax)  Lack waterproof exoskeleton Diplopoda (millipedes)  Terrestrial and herbivorous  Distinct head  One pair of antennae and one pair of mouthparts (jaws)  Numerous of small limbs (two pairs for each segment) Chilopoda (centipedes)  Terrestrial and carnivorous  One pair of antennae and one pair of mouthparts (jaws)  Distinct head  One pair of legs on each segment Arachnida (examples: scorpion, spider, mites, ticksชิโร่)  Terrestrial and carnivorous  Body is divided into cephalothorax and abdomen  Four pairs of walking legs  One pair of appendages to capture prey and one pair sensory appendages (palps) Insecta (examples: locusts, fleas, beetles, aphids, bees, ants)  Terrestrial  Distinct head, thorax, and abdomen  Three pairs of mouthparts and one pair of antennae  Three pairs of walking legs  Adults usually have wings

Nematodes (roundworms) (Example: Ascaris) • General Characteristics o o o

Unsegmented cylindrical bodies Mouth+Anus Separate sexes

Mollusca • General Characteristics o o o

Mantle Unsegmented (with head, foot, visceral hump – central mass of internal organs) Have shells containing calcium carbonate (calcareous shell)

• Classes o

o

o

Gastropoda (Example: Garden Snail)  Distinct eyes, head, sensory tentables  Shells (often single-coiled)  Radula (tongue-like organ armed with rows of teeth for feeding) Pelecypoda (Examples: Oysters, clams, scallop, mussels, cockles)  Reduced Head  No tentacles  Filter feeders Cephalopoda (Example: Octopus)  Conspicuous head with well developed eyes and tentacles  Beak and a radula for feeding  Fast-moving/Most intelligent invertebrate

Echinodermata (Example: Starfish (Asterias), sea cucumbers, sea urchins) • General Characteristics o o o o

Marine mammals with 5 way radial symmetry Water vascular system Tube feet for locomotion (slow-moving) Spiny-skin

Chordata • General Characteristics o o o o o

Notochord (slender, stiff, flexible rod running along the back later replaced by backbone) Dorsal hollow nerve cord Visceral clefts (Reduced or modified in other chordates/ becomes gills in fish) Post-anal tail (maybe reduced or lost in some adult chordates) Triploblastic coelomate, bilaterally symmetrical, metamerically segmented

(Class ของ fish ไม่น่าจะออกนะ) • Problems of changing from living in water to land o

Move in low-density medium = little support

o

Breathe air (without desiccation แห้งตาย)

o o

Reproduce out of water Cope with variable environmental conditions

• Locomotion on land o

Have bony endoskeleton and being tetrapods (4-limbed)

• Gaseous exchange o o o

Lungs (Amphibians = also breathe through skin) Uric acid nitrogenous waste helps to conserve water (for birds and reptiles) Urine (Urea) for others (conserve no efficiently as uric acid waste)

• Reproduction o o

Amphibians breed where there is water, the larval stage leaves in water (most have external gills) Reptiles, birds, mammals have evolved an egg surrounded by protective membranes

• Environmental variation o

Evolved endothermy (the ability to maintain a constant body temperature)

Vertebrata… Pisces Amphibia Reptilia Aves Mammalia Habitat Aquatic Aquatic+Terrestrial Aquatic+Terrestial Terrestrial Terrestrial Limbs Fins Yes Yes Fore/back Yes Respiration Gills Gills/Fins Lungs Lungs Lungs Skin Scales Soft moist + mucus Rough thick scaly Feathers Hairs Heart 2 3 3-4 4 4 Body temp. Exo. Exo. Exo. Endo. Endo. Circulation 1 2 2 2 2 Nitro. Wastes Ammonia Urea Uric Acid Uric Acid Urea Fertilization External (H2O) External (H2O) Leather-shell egg Hard-shell egg Young *The information above is for “most” animals but not all! There are some exceptions such as mammalia (some are aquatic such as dolphins and whales)

Biology Exam: Short-Note Chapter 22