Factors limiting the use of draught power
Unavailability of draught animals Conservativeness of some farmers to adopt to draught technology Availability of alternative sources of power like human labor. Lack of capital ... Read More
advantages of using animal draught power
They are economical on small, scattered plots They are cheap to buy and use, does not require fuel Draught powered technology requires little skill Draught ... Read More
Factors to consider when choosing a draught animals
Power output: animals with high power output are mostly preferred for use in traction Amount of traction: the animal should be able to give fair ... Read More
Factors that limit the use of pesticides by farmers.
they and application equipment are expensive application of pesticides requires skill especially in measuring and mixing they kill beneficial organism as well for example pollinator. ... Read More
Desirable characteristics of a pesticide
toxic to the target organism specific to the target organism biodegradable not to accumulate in the environment harmless to the plants and animals cheap and ... Read More
Timitation using progeny testing to select animals
The animal has to grow and produce offspring therefore takes a long time The performance of the offspring may be due to other factors other ... Read More
Situations in which progeny testing is used to select animals
When the character of the parents can be determined after slaughter When selecting animal for weakly inherited traits When selecting animals for traits expressed in ... Read More
Tandem selection method in agriculture
The selection in which several traits are improved in succession, such as selection is carried out first for one trait, until a desired genetic level is ... Read More
Progeny testing in agriculture
It refers to evaluation of bulls on the basis of their daughter's performance. it is commonly used to assess the breeding of the males in ... Read More
Pedigree selection in agricutural animal selection
This is the evaluation and selection animals only on the basis of performance of their parents and grandparents/ancestors. The ancestral records are used to predict ... Read More
Individual selection of animals in agriculture
It is the selection of animals basing on their performance and appearance. The animals' genetic potential is based on the animals' performance. This aid is ... Read More
Reasons why the supply of an agricultural commodity may be low even when the demand for it is high.
Bulkiness of the products making it difficult to transport to places where they are demanded Lack of method of preservation to sell in time of ... Read More
Types of herbicides
Translocated herbicides move to the site of action via the transport mechanisms within the plant; the xylem and phloem. The xylem transports water and nutrients from ... Read More
Explain why the reactivity of alcohols with hydrogen halides is in order; tertiary > secondary > primary alcohols.
Hydrogen halides react alcohols via formation of carbonium ions Tertiary alcohols react fast because tertiary carbonium ions are stable readily formed from tertiary alcohols; and ... Read More
Explain why alcohols are neutral organic compounds whereas phenol is weakly acidic, and yet both have hydroxyl groups.
The alkyl group in alcohol has a positive inductive effect; it pushes electrons towards OH group and stabilizes O – H bond preventing it from ... Read More
Explain why Magnesium ions form precipitate with dilute ammonia solution, but no precipitates is formed if ammonium chloride is added to magnesium ions prior to ammonia solution
Ammonia hydrolyses in water to hydroxyl ions NH3 (aq) + H2O (l) → NH4+(aq) + OH-(aq) Hydroxyl ions react with magnesium ions to form white ... Read More
Why is the boiling point of water higher than that hydrogen fluoride?
Water has higher boiling point than hydrogen fluoride because each water molecule has two hydrogen atoms and two lone pairs on the oxygen atom; this ... Read More
Difference between Guard cells and epidermal cell
Guard cells Epidermal cells Has chloroplast Lacks chloroplast Prominent nucleus Less prominent mixture Kidney shaped Irregularly shaped Uneven thick walls Uniform cell wall Dense cytoplasm ... Read More
Factors that affect the rate of transpiration
(a) Environmental factors 1. Temperature: the higher the temperature, the higher the rate of transpiration due to availability of vaporization energy. 2. Humidity: high humidity ... Read More
Control of the beating of the heart
The beating of the heart Cardiac muscle is myogenic, that is, generate rhythmical contraction from within its muscle. The heart rhythm is initiated by specialized ... Read More
Parts and functioning of the heart
The heart Blood returning via the vena cava enters the right atrium. The resulting pressure in this chamber forces and opens the flaps of the ... Read More
Differences between arteries and veins
Arties and vein Arteries transport blood at high pressure to the body while veins transport blood at low pressure from the body to the heart. ... Read More
Open and closed circulation system
(a) The open vascular system: (most arthropods, some cephalad molluscs, tunicates). Blood is pumped by heart into an aorta which branches into a number of ... Read More
Transport of carbon dioxide in blood
CO2 reacts with water to produce carbonic acid H2CO3. In the red blood cells, the reaction is catalyzed by carbonic anhydrase. Carbonic acid dissociates into ... Read More
Adaptations of red blood cells to its function
1. They have a biconcave disc shape to increase the surface area for the absorption of oxygen. 2. They lack a nucleus, which permits hemoglobin ... Read More
Functions of mammalian blood
1. Transport of soluble organic compounds from the small intestine to various parts of the body. 2. Transport of soluble excretory matters to organs of ... Read More
Structure and functions of hemoglobin
Structure of hemoglobin Structure of hemoglobin Hemoglobin comprises four subunits, each having one polypeptide chain and one heme group. The polypeptide chains of adult hemoglobin ... Read More
Oxygen-carrying pigments
Pigment Metal in the prosthetic group Color of pigment Example of animals Hemoglobin Iron red vertebrate Plasma or cells Hemocyanin Copper blue arthropods ... Read More
Advantages/functions for circulatory systems in big animals
Supplies metabolites and removes waste products from the cells at a faster rate than diffusion would do. It enables separation of materials transported; e.g. oxygenated ... Read More
Adaptations of animals to live in cold environments
Hibernating is a behavioral response by many temperate and artic animals to very cold temperatures. The animal responds to a very cold temperature by going ... Read More
Adaptations of endotherms to the cold and hot environment.
Adaptations of endotherms to the cold environment. The animals develop large volume to surface ratio. i.e. the extremities such as ear tend to be small ... Read More
The response of endotherms e.g. man to cold and hot conditions
The response of endotherms e.g. man to cold conditions The hair is raised and brought into a more-or-less vertical position by contraction of erector pili ... Read More
Parts of the skin
The skin is divided into two main layers, the epidermis at the surface, and the dermis beneath. Below the dermis is another layer, not strictly ... Read More
How heat energy is lost or gained by animals.
Organisms lose or gain heat from the environment by four physical processes. Conduction is the transfer of heat energy from hotter to the cooler of ... Read More
Advantages and disadvantages of ectotherms
Advantage of ectotherms Low food consumption since it is not used to maintain body temperature. Bodies are less affected by wide environmental temperature variation ... Read More
Advantages and disadvantages of being endothermic animals
Advantages of being endothermic animals Survives in a wide range of environmental temperatures Metabolic reactions in the body are always carried out effectively no matter ... Read More
Why should animals regulate body temperatures?
The body temperature must be kept constant because enzymes work best at specific optimum temperature. For instance, human body temperature is about 36.90C which is ... Read More
Causes of seed dormancy
Seed coats impermeable to water: The seed of certain family have very hard seed coats which are impermeable to water. This dormancy remains until the ... Read More
Adaptations of fruits to animal dispersal
May have sticky hairs e.g. Desmodium May have hooks to stick on fur Some fruits have attractive colour, scent and sweet mesocarp when ripe, e.g. ... Read More
Similarities and differences between sexual reproduction in flowering plants and animal
Similarities between sexual reproduction in flowering plants and animal Gamete formation Start from germ cells/unfertilized sell Gamete formation is by meiosis More than one male ... Read More
Adaptations promoting self-fertilization
Bisexual, hermaphrodite flowers e.g. marigold. Anther and stigma ripen at the same time. E.g. tomato. Flowers remain enclosed until fertilization has taken place. E.g. garden ... Read More
Advantages and disadvantages of reproduction by seed
Advantages of reproduction by seed The plant is independent of water for sexual reproduction and therefore better adapted for land environment. The seed protects the ... Read More
Means employed by plants to limit self-fertilization in plants
Dichogamy: anthers mature, and stigma become receptive at different times Protandry: anther mature before the stigma Protogyny: stigma mature before the anther Self-incompatibility: the pollen ... Read More
Advantages and disadvantages of self- fertilization
Advantages of self-fertilization: it increases the chances of fertilization and formation of new organism. only one parent is required, and that beneficial qualities are more ... Read More
Parthenocarpy-meaning
This is the development of a fruit without fertilization such fruits cart be artificially produced for commercial purpose by spraying with auxins. Please find free ... Read More
Parthenogenesis-meaning
This is the development of a new offspring from unfertilized egg. Haploid parthenogenesis, the egg is produced by meiosis egg in bees whereas in diploid ... Read More
Parts of ovule
Diagram of an ovule Functions of parts ovary Stalk/funiculus allows passage of food and water to the growing ovary Ovary wall protects the ovule Egg ... Read More
Ovum formation in plants
Please find free downloadable notes, exams and marking guides of agriculture, biology, Physics, chemistry etc. from digitalteachers.co.ug website. Dr. Bbosa Science Read More
Parts of mature pollen grain
Please find free downloadable notes, exams and marking guides of agriculture, biology, Physics, chemistry etc. from digitalteachers.co.ug website. Dr. Bbosa Science Read More
Sexual reproduction in plants
The flower The flower is the sexual reproducing organ of the flowering plants. It is divided into 3 parts Perianth: These surround the male ... Read More
Factors affecting the Basal metabolic rate (BMR) in man
Body size: Metabolic rate increases as weight, height, and surface area increase. Body composition: Fat tissue has a lower metabolic activity than muscle tissue. As ... Read More
10Differences in aerobic and anaerobic respiration
Aerobic Respiration Anaerobic Respiration Definition Aerobic respiration uses oxygen. Anaerobic respiration is respiration without oxygen; the process uses a respiratory electron transport chain but ... Read More
Glycolysis in respiration
Glycolysis is the first stage of breakdown of glucose in anaerobic and aerobic respiration; it occurs in in absence of oxygen. Glycolysis represents a series ... Read More
Uses of ATP in the body
Provide energy to build up macromolecules such as proteins from amino acids, polysaccharides form monosaccharides and DNA synthesis. Provide energy for movement of materials such ... Read More
Respiration (A-level notes)
Respiration for A-level This is the oxidation of organic substance to liberate energy in the body. Aerobic respiration requires oxygen whereas anaerobic respiration does not ... Read More
Similarities and differences between sexual reproduction in flowering plants and animal
Similarities between sexual reproduction in flowering plants and animal Gamete formation Start from germ cells/unfertilized sell Gamete formation is by meiosis More than one male ... Read More
Causes of infertility in female
Failure of ovulation Most cases of female infertility are caused by problems with ovulation. Without ovulation, there are no eggs to be fertilized. Some signs ... Read More
Causes of Infertility in men
A problem called varicocele (VAIR-ih-koh-seel). This happens when the veins on a man's testicle(s) are too large. This heats the testicles. The heat can affect ... Read More
Effects of progesterone during pregnancy
Growth of mammary glands Inhibits FH release Inhibits prolactin release Inhibits contraction of the myometrium Please find free downloadable notes, exams and marking guides of ... Read More
Effects of estrogen during pregnancy
promotes the growth of mammary glands inhibits FSH release Inhibits prolactin release Prevents implantation in the uterus Increases size of the uterine muscle Increase ATP ... Read More