Advice TC

Bones cannot move without muscles. Cell contraction is the changing of the

Shape of the cell. If a cell contracts in one direction, it lengthens in another direction. Some cells are designed to contract, these are muscle cells, which are found in most animals. These types of movements rely on biochemical systes involving tubulin and microtubules. Another basic cell movement depends on the protein actin found in the eukaryotic system. Actin fibers cause movement in the cytoskeleton and cell mambrane, using energy which comes from ATP.

A. Muscle groups

There are three types of muscles

1. Smooth muscles

Smooth, glistening in appearance, also called involuntary muscle. Found in various internal organs such as in the walls of blood vessels and the digestive tract.

2. Cardiac Muscle or Heart Muscle

Has control centers of its own

3. Skeletal Muscle

Striated or voluntary muscle. These muscles are controlled by the somatic nervous system. They can contract much more rapidly than smooth muscle or cardiac muscle, but they cant stay contracted for long periods. Skeletal muscles are multinucleated; the nuclei lay just beneath the cell surface.

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C. A.Introduction

The earth presents animals with two problems:

1. It is quite different from place to place. Some areas are suitable for living and other places are not.
2. The earth has gravity. Animals with a stiff skeletal system can resist the downward pull. Structures are often movable and serve as places of attachment for muscles that help animals move from place to place.

D. B. Types of Skeleton systems

1. Hydrostatic skeleton

Fluid is held under pressure in a closed body compartment seen in coelenterates, flatworms, nematodes and annelids. The animals control movement by changing the shape of the body compartment with muscles.

1. Exoskeleton

Hard encasement deposited on the surface of an animal. Mollusks have a shell secreted by the mantle. Arthropods have a jointed exoskeleton secreted by the epidermis. About 30-50% of the cuticle is made of chitin. Some arthropods add calcium salts to the chitin.

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5. Class: amphibia

there are 4,000 species of modern amphibians, represented by three orders:

a. Urodela

Salamanders

b. Anura

Frogs and toads

c. Apodia

Worm-like caecilians

Nearly all amphibians reproduce and develop in aquatic habitats. They have moist and highly vascularized skin. The skin is the most important organs of the repiratory exchange in spite of the presence of lungs in most. They have a three chambered heart. Most frogs and toads are external fertilizers, but salamanders and caecilians are internal fertilizers. Most amphibians are oviparous with external fertilization. However, some are viviparous or ovovipaous.

6. Class: Reptilia

there are 7000 species of reptiles which are represented by three important orders.

a. Chelonia

Turtles

b. Crocodilian

Crocodiles, alligators, and relatives

c. Quamata

Lizards and snakes

Reptiles are conceived, live and die on land. Since they are the first fully terrestrial group of vertebrates and therefore, have specialized organs for life on land. They female reptiles retained a cloaca, but the male has developed a penis for copulation and internal fertilization. The amniote egg is porous, leathery and complete with food and fluids( parts: yolk, allantois, chorion, and embryo).

Reptiles convert nitrogenous wastes to uric acid rather than ammonia. Ammonia is less toxic, but requires a large amount of water. The skin is dry with protective scales, reducing water loss. There are few mucous secreting glands. Most have a three and a half or four chambered heart, with 2 atria and a ventricle with a partial spetum. The crocodile has a complete spetum and a four chambered heart. Most reptiles are carnivorous. They locate food by sight, heat detecting, olfactory and hearing.

7. Class: Aves (birds)

There are 8,600 species of birds. They have a light skeleton with many hollow bones. The reptilian teeth have been replaced by a light horny beak, the neck is long and flexible, the bones of the trunk are fused together, and their breast bone is enlarged which acts as a large keel for the attachment of flight muscles. The birds tail is small, made only of four vertebrae, legs are adapted for perching and grasping. Feathers evolved from reptilian scales. The feathers are strong for their weight because of their interlocking barbs. Birds have a complicated respiratory system and lack a urinary bladder; both solid waste and liquid waste are added together. The female has only one ovary to produce eggs. Birds have a four chambered heart.

8. Class: Mammalia (mammals)

Mammals are fury or hairy animals that produce milk. There are three groups of mammals: montremes( egg laying), marsupials ( pouched animals), and placentals.

Mammals use a muscular diaphragm to move air. They have a four chambered and lungs fertilization and development is usually internal(except for montremes). Females have separate urinary and reproductive tracts. Mammals may have specialized teeth. Milk is modified sweat which provides the young with high protein, high coloric nutrients.

Annelids are bilateral protosomes. These organisms are divided into body segments called metameres. These are separated by septa on the inside. Annelids have a segmented coelom, tubular gut, closed circulatory system, paired nephridia for the excretory system, and a centralized nervous system with specialized sensory cells.

There are three classes of Annelids.

1) Class Oligochaeta: Earthworms

The earthworm body is compartmentalized into regular segments. Most of the segments are identical. Each identical segment contains two nephridia, three pairs of nerves branching off from the central nerve chord, a portion of the digestive tract, a left and right coelomic cavity, and four pairs of bristles (setae). There are also segments that contain specialized areas of the nervous, circulatory and reproductive systems.

a. Digestive System

Mouth, pharynx (suction pump), esophagus, crop (stores food), gizzard (for grinding the food), intestine (with enzyme secreting cells and ciliated epithelial cells), and the anus.

b. Reproduction

Hermaphroditic. Mating partners join at the clitellum and exchange sperm. The sperm that is given is stored in seminal vesicles, while the sperm from the other partner is stored in the seminal receptacles.

c. Closed Circulatory System

The blood is enclosed in vessels. There is a dorsal and ventral blood vessel that is connected by five pairs of aortic arches (hearts) lying over the esophagus. The worms’ movement causes the arches to ‘pump’ the blood.

d. Nervous System

There are two large ganglia (brains) over the pharynx connected to a ventral nerve chord. The nerve chord has a smaller ganglia in each segment.

e. Excretory System

This consists of a pair of nephridia per segment necessary to remove excess water and nitrogenous wastes. The nephridium is ciliated, collecting funnel in the coelom. There is a tubule leading to the nephiridial pore.

f. Locomotion

Setae are small lateral bristles (four per segment) that aid movement.

2) Class Polychaeta: Marine Worms

Unique features include lateral appendages (parapodia) per segment, separate genders, a free-swimming larva (trohophore), no clitellum, and a well0developed head with tentacles and eyes.

3) Class Hirudinea: Leeches

These are mostly found in fresh water in tropical regions and are mostly blood suckers. There is no head, except for a sucker around the mouth and cutting jaws. There are no setae or parapodia on segments. The leeches secrete hirudin which is an anticoagulant.

These protosomes exhibit a bilateral symmetry, are unsegmented, and have a true coelom. Some of their unique features include a muscular foot, mantle, radula, and gills for breathing

1. Characteristics

a. Body Zones

1) Head-Foot: contains both the sensory and motor organs

2) Visceral mass: well developed organs of digestion, excretion, and reproduction

3) Mantle: specialized tissue formed from the folds of the dorsal body wall. The mantle hangs over and enfo0lds the visceral mass and secretes the shell.

b. Mantle Cavity

The mantle cavity is the space between the mantle and the visceral mass, it houses the gills. The digestive, excretory, and reproductive systems discharge into the mantle cavity. Water sweeps into the mantle cavity, passing across the surface of the gills, aerating them. Then leaves the mantle cavity carrying the excrement and gametes (in season) with it.

c. Radula

This is a movable, tooth bearing strip of chitinous material that suggests a tongue. The radula scraps food material and can be used in combat.

d. Hard Shell

The shell is made up of calcium carbonate.

e. Supply Systems

f. Circulatory Systems

These consist of a muscular pumping organ, the heart, and vessels that carry the blood to and from the heart. The heart has three chambers: two atria and one ventricle. Mollusks other than cephalopods have an open circulatory system, ie. The blood is not contained in vessels. The blood is collected from the gills, pumped through the heart, and released directly into spaces in the tissues. The blood then returns to the gills then to the heart. The blood-filled spaces are known as the hemocoel. In mollusks, the hemacoel has almost completely replaced the coelom. The small area around the heart and cavities in the reproductive and excretor system are part of the coelom.

g. Respiration

Oxygen enters the body through the moist surfaces of the mantle and the

gills. The gill is an external structure with an increased surface area

where gas can diffuse.

h. Digestion

The digestive tract is extensively ciliated. Food is taken up by the cells

lining the digestive glands which arise from the stomach and anterior

intestine and enters the blood. Undigested material is discharged through

the anus.

i. Excretion

Nitrogenous wastes produced by metabolic activities are removied by nephridia.

2) Class: Bivalvia (Clams, Mussels, Oysters)

The body is in a hinged shell which is secreted by the mantle. Adductor muscles

close and open the shell. They have an open circulator system. There is no head

or brain, but there are pairs of ganglia around the body. A radula is not present.

Separate genders and the zygote develop into a trochophore larva, as in

polychaetes.

3) Class Gastropoda (Univalves: Snails, Slugs, Abalones, Limpets,

Nudibranchs)

The mantle secretes a shell. There is a well developed head with two pairs of tentacles. The first pair is for touch and the second pair has light-senstive eyes at tip. The radula scrapes food. The land snails breathe by using the mantle cavity, rich in blood vessels, as the lung. Some members are hermaphrodites (nudibranchs, sea hares, sea slugs, pteropods), but most have separate genders. Snails can host fluke parasites. The snails are asymmetrical due to torsion. Torsion is the twisting of a shell through 180° of the rest of the body relative to the head, resulting in the snail’s mantle cavity and visceral mass moving to a position over the head.

2) Class: Cephalopoda (Octopus, Squid, and Nautilus)

The foot is divided into arms and /or tentacles with suckers. The nautilus has many tentacles, the octopus has eight and the squid has ten. The nautilus has an external an external shell, the squid an internal shell (pen) and the octopus no shell. Cephalopods move rapidly by jet propulsion of water from the siphon.

These organisms have a closed circulatory system with two types of hearts. The arterial heart pumps blood throughout the body and there are two gill hearts to receive blood from the body and pump it to the gills. Cephalopods have a well developed head and brain with organs for balance and an eye similar to ours. The mouth has a radula and a jawlike beak.

Roundworms have three tissue layers that from a pseudocoelom. This pseudocoelom functions as a hydroskeleton.

1. Circulatory System

Roundworms lack a circulatory system. Contraction of muscles move the fluid.

2. Digestive System

Roundworms have a one-way digestive system with two openings.

3. Reproduction

Both sexes are present. The female is usually larger than the males. The fertilization of the eggs is internal, and the female may deposit 100,00 fertilized eggs per day. The zygotes are resistant to harsh conditions.

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These animals have bilateral symmetry. There are acoelomate with three tissue layers which give rise to specialized organs. There are three classes of flatworm.

1. Class turbellaria: Planaria

a. Digestive system

They have a mouth, pharynx, and a branched gastrovacular cavity. There is one opening, but two-way traffic. Planarians are carnivorous. Through muscular contractions, the planaria sucks in small pieces of meat.

b. Respiration

Gas exchange is accomplished by diffusion through the skin.

a. Excretion

Water balance is regulated by flame cells that sweep excess water and nitrogenous wastes (ammonia) into tubules and out of the body through pores.

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A. ANIMAL CHARACTERISTICS

1. They are heterotrophic, multicellular, and eukaryotic.
2. They are organisms that store carbohydrates as glycogen.
3. They are organisms that lack cell walls. The intracellular junctions (tight junctions, desmosomes, and gap junctions) are found only in animals.
4. These organisms have muscle and nervous tissue.
5. These organisms reproduce sexually. They have a dominant diploid organism that produces gametes, either a flagellated sperm or a large, nonmotile egg. These gametes fuse and undergo mitosis to form a hollow ball called a blastula. This blastula undergoes gastrulation; then the embryonic tissues differentiate.
6. Organisms whose life cycle may include many larval stages. Larva is a free-living sexually immature form. The larva is morphologically different from the adult. The larval form usually eats different foods and may live in different habitats. The larva will eventually undergo metamorphosis and change into the adult form.

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M. PLANT TOUCH RESPONSES

In the sensitive plant, the petiole drops and the leaflets fold a second or two after the leaf is touched. This is due to the sudden change in turgor pressure of specialized ‘motor cells.’

In the Venus flytrap, the movement is the result of acid growth. The insect brushes against trigger hairs, and this activates enzymes that pump H+ into the epidermal cells along the outer surface of the trap hinge. The quick acidification of the cell walls causes the trap to close. The other cells on the inner surface of the hinge grow at a regular rate, and when the plant opens 10 hours later, the leaf is slightly larger.

General touching (systematic rubbing or bending) of plants stems inhibits elongation. This results in progressively shorter plants.

N. CHEMICAL COMMUNICATION AMONG PLANTS

Angiosperms can produce toxic or bad-tasting compounds. This is a defense against herbivores and insects that chew.

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The response of plants to the length of periods of light and darkness.

1. Types of plants

a. Day-neutral (flower without regard to the day length)

b. Short-day (flowers only when the light period is shorter than critical length)

c. Long-day (flowers only when the light period is longer than critical length)

Short day plants require 1 hours or less of light to flower. Long day plants require 14 hours or more of light to flower. Day neutral plants are unaffected by day length. These plants will flower when a certain level of maturity has been reached.

2. Measuring the Dark

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