Tag: Dr. Bbosa Science

Control of the beating of the heart

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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

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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

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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

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(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

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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

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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

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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

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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

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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

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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

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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.

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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

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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

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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.

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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

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  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

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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?

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

10Differences in aerobic and anaerobic respiration

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  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

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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

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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)

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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

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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

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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

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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

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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

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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

Hormonal control of spermatogenesis

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The hypothalamus secretes gonadotrophin-releasing hormone or GnRH, that stimulates the anterior pituitary gland to produce the gonadotrophic hormones, i.e. Luteinising hormone (LH) and follicle-stimulating hormone ... Read More

The hormonal control of birth

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Towards the end of pregnancy, the levels of estrogen in the blood rise while that of progesterone falls. It has been suggested that this plays ... Read More

Why should mother’s and fetal blood not mix

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To prevent blood incompatibility due to different blood group To prevent incompatibility due to different rhesus factors To prevent infections from the mother attacking the ... Read More

Adaptations of the placenta to its functions

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Rich blood supply allows absorbs necessary nutrients and deliver waste products to the mother’s drug Has villi that increase surface area for exchange of material ... Read More

Advantages and disadvantages of internal fertilization

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Internal fertilization This is the union of male and female gametes inside female animal The advantages and disadvantages of internal fertilization Advantages • more chances ... Read More

Feature leading to variations in sexual reproduction

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Reciprocal crossing over of genes between chromatids of homologous chromosomes may occur during prophase I of meiosis. This produces new linkage groups and provides some ... Read More

Comparison of gamete formation in male and female organs in man

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Male organ Female organ 1. Production of sperms begins at puberty Production of ova begins before birth completed after fertilization 2. Several primordial germ cells ... Read More

Parts of a sperm and an ovum

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  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

Oogenesis in human

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Oogenesis occurs in the overlies of female, Primordial germ cells (2n) divide mitotically to form oogonia the grow into primary oocytes (2n) primary oocytes undergo ... Read More

Spermatogenesis inhuman

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Spermatogenesis in man occurs in the testis; Primordial germ cells (2n) divide mitotically to form spermatogonia that grow into primary spermatocyte (gamete forming cells) with ... Read More

Application of conductivity measurements

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Determine end points in conductometric titration To find concentration of solutions Determine salinity of water Please find free downloadable notes, exams and marking guides of ... Read More

Importance of classification of organisms

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It provides a way of identifying different groups of organisms. It gives an internationally recognized way of referring to a particular organism. It helps in ... Read More

Role/importance/effects of ethene on plants

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Ethene Promotes fruit ripening by promotes the conversion of starch to soluble sugars and triggers a sudden and dramatic increase in the respiration rate which ... Read More

Role/importance/effects of Abscisic acid (ABA) on plants

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Abscisic acid is a major inhibitor in plants and is antagonistic to all the three classes of growth promoters. Role of abscisic acid Maintains leaf ... Read More

Role/effects/importance of Cytokinins in plants

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Cytokinins is a class of growth substances that promote cell division.  They do so, however in the presence of auxins.  Gibberellins may also play a role, ... Read More

Role/effects/importance of Gibberellins in plants

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Gibberellins is class of growth promoters produced particularly in young epical leaves (possibly in chloroplasts), buds, seeds, and root tips.  They fall into a group of ... Read More

Phototropism

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The growth response towards the light from one direction. Shoots grow towards unidirectional light and are said to be positively phototropic. Most roots do not ... Read More

Taxes response in plants

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Taxes: - is a movement of an entire cell or organism (i.e. locomotion) in response to and directed by an external stimulus.  Tactic responses can ... Read More

Nastic responses in plants

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Nasties: -  is a non-directional movement of part of a plant is a response to an external stimulus. For example, “sensitive plant” Mimosa pudica is sensitive ... Read More

Experiment to demonstrate phototropism/effect of unidirectional light on the growth of shoot

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Select two potted seedlings of bean of equal age and size and water them. Place one of the seedlings in a box painted black on ... Read More