Terms in this set (393)

1. Prokaryotes range in size from 1-10 µm in length and from 0.7-1.5 µm in width.
2. "Prokaryote" means "before a nucleus"—their cells lack a eukaryotic nucleus.
3. Prokaryotic fossils date back as far as 3.5—3.8 billion years ago.
4. Fossils indicate prokaryotes were alone on earth for 2 billion years; they evolved very diverse metabolic capabilities.
5. Prokaryotes adapted to most environments because they differ in the many ways they acquire and utilize energy.
6. Outside the plasma membrane of most cells is a rigid cell wall that keeps the cell from bursting or collapsing due to osmotic changes by peptidoglycan, a complex molecule containing a unique amino disaccharide and peptide fragments.
a. The cell wall may be surrounded by an organized capsule called a glycocalyx and/or by a loose gelatinous sheath called a slime layer.
b. In parasitic forms, these outer coverings protect the cell from host defenses.
7. Some prokaryotes move by means of flagella.
a. The flagellum has a filament composed of three strands of the protein flagellin wound in a helix and inserted into a hook that is anchored by a basal body.
b. The flagellum is capable of 360o rotation which causes the cell to spin and move forward.
8. Many prokaryotes adhere to surfaces by means of fimbriae.
a. Fimbriae are short hairlike filaments extending from the surface.
b. The fimbriae of Neisseria gonorrhoeae allow it to attach to host cells and cause gonorrhea.
Prokaryotic cells lack the membranous organelles of eukaryotic cells.
10. Various metabolic pathways are located on the plasma membrane.
Diversity of Living Reptiles
a. Most reptiles today live in the tropics or subtropics; lizards and snakes live on soil; turtles, crocodiles and alligators live in water.
b. Turtles have a heavy shell fused to the ribs and to the thoracic vertebrae.
1) Turtles lack teeth but use a sharp beak.
2) Sea turtles must return to lay eggs onshore.
c. Lizards have four clawed legs and are carnivorous.
1) Marine iguanas on the Galapagos are adapted to spend long times in the sea.
2) Chameleons live in trees, have a long sticky tongue to catch insects, and change color.
3) Geckos are nocturnal and have adhesive pads on their toes.
4) Skinks have reduced limbs and shiny scales.
d. Snakes evolved from lizards and lost legs as an adaptation to burrowing.
1) Their jaws can readily dislocate to engulf large food.
2) A tongue collects airborne molecules to transfer them to Jacobson's organ for tasting.
3) Some snakes are poisonous and have special fangs to inject venom.
4) Snakes have internal ears that can detect low-frequency sounds and vibrations.
e. Tuataras are lizardlike animals found in New Zealand.
1) They possess a well-developed "third eye," which is light sensitive and buried beneath the skin in the upper part of the head.
2) They are the only member of an ancient group of reptiles that incuded the common ancestor of modern lizards and snakes.
f. Crocodiles and alligators are largely aquatic, feeding on fishes and other animals.
1) Their powerful jaws have numerous teeth; a muscular tail is both a paddle to swim and a weapon.
2) Male crocodiles bellow to attract mates; males of some species protect the eggs and young.
The Phosphorus Cycle
1. In the phosphorus cycle, weathering makes phosphate ions (PO4 and HPO42 ) available to plants that take up phosphate from the soil.
2. Some of this phosphate runs off into aquatic ecosystems where algae incorporate it into organic molecules before it is entrapped in sediments.
3. Phosphate that is not taken up by algae is incorporated into sediments in the oceans.
4. Sediment phosphate only becomes available when geological upheaval exposes sedimentary rocks.
5. Phosphate taken up by producers is incorporated into a variety of organic compounds.
6. Animals eat producers and incorporate some of the phosphate into phospholipids, ATP, and nucleotides of DNA; however what is in teeth, bones, and shells does not decay for long periods.
7. Decay of organisms and decomposition of animal wastes eventually makes phosphate ions available again.
8. Available phosphate is generally taken up quickly; it is usually the limiting nutrient in most ecosystems.
9. Human Activities and the Phosphorus Cycle
a. Humans boost the supply of phosphate by mining phosphate ores for fertilizers, detergents, etc.
b. Run off of animal wastes from livestock feedlots and commercial fertilizers from cropland as well as discharge of untreated and treated municipal sewage can all add excess phosphate to nearby waters.
c. Eutrophication is the name of this over-enrichment that leads to algal blooms; when the algae die off, decomposers use up all of the oxygen and this can cause a massive fish kill.
Tropical Forests
1. Tropical rain forests are found in South America, Africa, and the Indo-Malayan region near the equator.
2. The climate is warm (20o-25o C) and rainfall is plentiful with a minimum of 190 cm per year.
3. This is probably the richest biome, both in number of species and in their abundance.
4. A tropical rain forest has a complex structure, with many levels of life.
5. Although there is animal life on the ground (e.g., pacas, agoutis, peccaries, and armadillos), most of the animals live in the trees.
6. Insects are abundant in tropical rain forests; the majority have not been identified.
7. Termites are critical in the decomposition of woody plant material.
8. Various birds tend to be brightly colored.
9. Amphibians and reptiles are represented by many species of frogs, snakes, and lizards.
10. Lemurs, sloths and monkeys feed on fruits.
11. The largest carnivores are cats (e.g., jaguars in South America and leopards in Africa and Asia).
12. Epiphytes are air plants that grow on other plants.
a. They have roots of their own to absorb moisture and minerals leached from the canopy.
b. Others catch rain and debris in hollows of overlapping leaf bases.
c. Common epiphytes are related to pineapples, orchids and ferns.
13. Tropical forests in India, Southeast Asia, West Africa, West Indies, and Central and South America are seasonal.
a. They have deciduous trees that shed leaves in the dry season; layers of undergrowth are below.
b. Certain of these forests contain elephants, tigers and hippopotami.
14. A year-long growing season and high temperatures mean productivity is high.
15. But the warm, moist climate that supports high productivity also promotes rapid recycling of litter.
16. The soil is called laterite and the iron and aluminum oxides give it a red color and a brick texture when it bakes in the hot sun.
17. Consequently the soil is relatively poor because the nutrients are rapidly cycled into the biomass; this makes a poor agricultural soil.
1. Lakes are freshwater bodies classified by their nutrient status.
a. Oligotrophic (nutrient-poor) lakes have low organic matter and therefore low productivity.
b. Eutrophic (nutrient-rich) lakes are highly productive from natural nutrients or agricultural runoff.
c. Eutrophication occurs when added nutrients change an oligotrophic lake to eutrophic; this process is called eutrophication.
2. In the temperate zone, deep lakes are stratified in summer and winter.
a. Epilimnion is the surface layer warmed from solar radiation; it soon becomes nutrient-poor but photosynthesis keeps oxygen levels high.
b. At the thermocline, there is an abrupt drop in temperature.
c. The hypolimnion is the lower cold region; it becomes depleted in oxygen but is nutrient rich from detritus falling from above.
d. The less dense epilimnion floats on the heavier cold hypolimnion; this prevents mixing.
3. Fall and Spring Overturns
a. In the fall, the upper epilimnion waters become cooler than the hypolimnion.
b. This causes the surface water to sink and deep water to rise.
c. This fall overturn continues until the temperature is uniform.
d. In the winter, ice forms on top because ice is lighter; this provides an insulating cover and organisms can live through a harsh winter in this moderate water.
e. In spring, the ice melts and the cooler water on top sinks below the warmer water on the bottom.
f. After the spring overturn, water returns to a more uniform temperature and sun warms the surface.
g. Fish and other aquatic life are adapted to the strata and seasonal changes; for instance, cold water fish move deeper in the summer.