F.2.1 - F.4.2

F.2.1 - F.4.2 F.2.1 State that animals have been domesticated to produce breeds suitable for plowing, transport, food, fur, and skins, and for keeping as pets, providing one example of each. Plowing: oxen Transport: horses Food: turkeys Fur: sheep Skins: cows (leather) Pets: dogs F.2.2 Describe the rearing of an animal of economic importance using cattle, chickens, or sheep as an example. Cattle: The cows are raised on large farms. Their feed is carefully monitored to produce desired results. Sometimes growth hormones or other chemicals like antibiotics are added to the feed in order to make the cows more beefy and grow faster. They are allowed to graze in fields as well where they can roam and interact with other cows. Veterinarians are employed in order to attend to sick and injured animals. F.2.3 Discuss intensive animal rearing techniques in terms of yield and ethical issues. Most pig and chicken raising is done in large indoor facilities where food is carefully measured out to get a desired result from the animals. Chickens are often kept in cages and cattle for veal in crates. Ethical issues arise with these techniques since animals may not be allowed to leave their cages and get exercise or perform normal animal behaviors. It is not unheard of for large cattle companies to use techniques like artificial insemination (AI) and embryo collecting to increase livestock numbers. This can raise ethical issues such as the stress these procedures put on animals. For instance, AI is easy to do with cattle but requires invasive surgery with sheep and pigs and it may be done more than once in an animal. Also, some intensive techniques can be expensive and therefore feasible for only large firms that may threaten small farmers economically. F.2.4 Explain how veterinary techniques have been applied to improve the health and fecundity of animals. Animals are vaccinated against diseases and are given nutritional supplements in order to produce more healthy yields. AI can be used to ensure that females give birth on a regular basis to increase yields. In animals like cows, which normally give birth to one offspring at a time, animals may be induced to produce twins or triplets. F.2.5 Discuss the use and misuse of antibiotics and growth hormones in livestock production. Growth hormones are put into some animals' feed in order to make them grow faster and have more meat to therefore increase production. Antibiotics may be put into feed in order to help keep animals healthy and reduce veterinary costs. Use of antibiotics in animal feed may result in certain diseases to become resistant to antibiotics, facilitating their passage from animals to humans. Also, use of antibiotics may allow farmers to keep their animals in unsanitary conditions. Some growth hormones are known to cause cancer in humans, and can cause environmental danage.

F.3.1 Distinguish between plant growth regulators (plant growth hormones) and fertilizers. Plant growth regulators are chemicals produced by the plant to promote or inhibit growth in response to different kinds of environmental stimuli. These may include auxin, cytokinins, gibberellins, abscisic acid, and ethylene. Fertilizers simply are nutrients the plant needs that may or may not cause growth by their introduction to the soil and their subsequent intake up plants. F.3.2 Explain the role of auxin in phototropism as an example of the control of plant growth. Though it has been recently disputed, the generally accepted idea is this: when plants are illuminated intensely from one side, it causes auxin to be moved to the other side (the darker side). Auxins cause cell elongation, so by elongating the darker side but not the lighter side, the plant grows toward the light. F.3.3 Describe the role of auxins in terms of apical dominance and how pruning can result in a bushy, decorative plant. Auxins transported down the shoot from the terminal bud keep auxiliary buds from growing, producing apical dominance. If the plant is pruned, meaning the tip is cut off, nothing inhibits the terminal buds and a bushier plant results. F.3.4 Describe how plant growth regulators can be used commercially to promote rooting, to kill weeds, to induce fruit ripening at the required time, and to produce fruits without seeds. Auxins and cytokinins working together promote root growth. Powders may be added to soil containing these to induce root growth from parts cut off from other plants. Auxins such as 2,4-D can be used to kill weeds, but some, like 2,4-D, have been banned due to environmental hazards. The gas ethylene is produced by plants for ripening fruit, but ethylene can be added to the air around a fruit to force it to ripen. The addition of gibberellins to plants can cause fruit to grow without a fertilized seed, making seedless fruit. F.3.5 Explain the techniques used in cloning by micropropagation. Micropropagation is the growing of plant tissues by traditionally old methods like grafting in a lab or greenhouse, which thereby creates a clone of the original plant since genetic code is identical. This is a fast way to reproduce plants. The clone is grown in a growth medium, which is designed to be the perfect conditions for plant growth. The plants are grown in aseptic conditions free of bacteria and fungi. Auxins may be used to promote root growth, cytokinins are added for shoot growth, and gibberellins are added to work with auxins to promote stem elongation. F.4.1 Define inbreeding, outbreeding, interspecific hybridization, polyploidy, and F1 hybrid vigor. Inbreeding: breeding of closely related individuals, usually to preserve traits.

Outbreeding: breeding of distantly related or unrelated individuals, often producing a superior offspring Interspecific hybridization: hybrids resulting of a combination of two different species Polyploidy: having more than one set of chromosomes F1 hybrid vigor: the increased presence of hybrid state in F1 generations of hybrid crosses F.4.2 Outline one example for each of the terms in F.4.1. Inbreeding: Certain animals may be inbred to maintain a "purebred" status like show dogs Outbreeding: may be used to combine certain desirable traits into a single line Interspecific hybridization: in Siberia and Far East Russia, hybrids of B. mycrophylla and B. alba have arisen. Polyploidy: Some plants like corn may be engineered to have polyploidy since that makes for a stronger plant. F1 hybrid vigor: in experiments with Hereford and Angus cows in Nebraska, 15/16 of the offspring from Hereford-Angus hybrids were Angus, resulting in the loss of 87% of hybrid vigor.