The spinal cord is located within the vertebral column and consist of the following: The grey matter forms the central part of the spinal cord. It consists of nerve¬cell bodies and intermediate nerve fibres. The white matter of the spinal cord carries sensory nerve fibers while the ventral root carries motor nerve fibers. Simple and […]
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Necessity for support and movement in animals. Animals move from place to place: In search of food. To escape from predators. To escape from hostile environment. To look for mates and breeding grounds. The skeleton, which is a support structure, helps to maintain the shape of the body. Movement is effected by action of muscles
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Structure The human eye is spherical in shape and situated within a socket or orbit in the skull. It is attached to the skull by three pairs of muscle, which also control its movement. It is made up of three main layers; sclerotic layer, choroid and the light sensitive retina. Sclerotic layer Outermost white part
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MAMMALIAN SKELETON – AXIAL SKELETON, SKULL, RIBS, VERTEBRAL COLUMN & BONES The mammalian skeleton is divided into two: Axial and appendicular. Axial skeleton is made up of the skull and the vertebral column. Appendicular skeleton is made up of the pelvic and pectoral girdles and limbs (hind limb and forelimbs). The Axial Skeleton This consists
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There are three types of muscles, located at various parts of the body. In order to function all use energy in form of ATP. These include smooth, skeletal and cardiac muscles.
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WHAT IS ENDOCRINE? Endocrine system consists of glands that secrete hormones. The glands have no ducts and are known as endocrine glands. Other glands are known as exocrine glands because they have ducts. The pancreas has an outer exocrine portion and an inner endocrine portion. Hormones are chemical substances, protein in nature which are secreted
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The Mammalian Ear The mammalian ear performs two major functions: Hearing and detecting changes in the positions of the body to bring about balance and posture. The ear is divided into three sections. The Outer Ear This consists of: An outer flap, the pinna which is made up of cartilage. The function of the pinna
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Animal dispersal Fleshy fruits are eaten by animals. Animals are attracted to the fruits by the bright colour, scent or the fact that it is edible. The seeds pass through the digestive tract undamaged and are passed out with faeces. E.g. tomatoes and guavas. Such seeds have hard, resistant seed coats. Others have fruits with
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The female reproductive system consists of the following: Ovaries Are two oval cream coloured structures found in lower abdomen below the kidneys. Oviducts. They produce the ova. Are tubes which conduct the ova produced by the ovaries to the uterus. Fertilization occurs in the upper part of the oviduct. Uterus What is uterus? Uterus is
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What is fertilization in animals? Fertilization is preceded by copulation in which the erect penis is inserted into the vagina. This leads to ejaculation of semen. The sperms swim through the female’s genital tract to the upper part of the oviduct. The head of the sperm penetrates the egg after the acrosome_ releases lytic enzymes
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What is reproduction in animals? Sexual reproduction involves the fusion of gametes. In animals two individuals are involved, a male and a female. Special organs known as gonads produce gametes. In males testes produce sperms while in females ovaries produce ova. The fusion of male gamete and female gamete to form a zygote is called
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Male Sexual Characteristics Testerone is the main androgen that stimulates the development of secondary sexual characteristics. Broadening of the shoulders. Deepening of the voice due to enlargement of larynx. Hair at the pubic area, armpit and chin regions. Penis and testis enlarge and produce sperms. Body becomes more masculine. Female Enlargement of mammary glands. Hair
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Examining the stages of mitosis About 2 mm of a root tip of onion bulb is cut off and placed on a microscope slide. A stain e.g. aceto-orcein is added and the root tip macerated using a scapel. A cover slip is added and observations made. Different stages of mitosis can be observed. Examining the
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Concept of Growth and Development Growth is a characteristic feature of all living organisms. Most multicellular organisms start life as a single cell and gradually grow into complex organisms with many cells. This involves multiplication of cells through the process of cell division. This quantitative permanent increase in size of an organism is referred to
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Auxins are produced by plant apices, i.e. root apex and shoot apex. They bring about cell elongation resulting in growth. They are diffusible substances which effect growth when in very small amounts. Roots require lower concentrations than shoots. The effect of auxins on the growth of roots and shoots has already been discussed. Auxins also
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What is Ecosystem? The community and the abiotic or non-living environment together make up an ecosystem or ecological system. In this system energy flow is clearly defined from producers to consumers and nutrient cycling takes place in paths that links all the organisms and the non-living environment. Biomass This is the mass of all the
Requirements Small plots/boxes, meter rule and seeds of beans (or green grams, peas, maize), Procedure Place some soil in the box or prepare a small plot outside the laboratory. Plant some seeds in the box and place it in a suitable place outside the laboratory (or plant the seeds in your plot). Water the seeds
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What are the conditions necessary for seed germination? Seeds can easily be destroyed by unfavourable conditions such as excessive heat, cold or animals. Seeds need certain conditions to germinate and grow. Some of these conditions are external, for example water, oxygen and suitable temperature while others are internal such as enzymes, hormones and viability of
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What is a food chain? A food chain is a linear relationship between producers and consumers. It represents the transfer of food energy from green plants through repeated stages of eating and being eaten. Types of Food Chain Grazing food chain – starts with green plants. Detritus food chain – starts with dead organic material
What is population estimation methods? It is important to find or estimate the sizes of the different populations in a habitat. Direct counting or head count which involves the counting of every individual is not always applicable for all organisms. e.g., it is impossible to count directly the numbers of grasshoppers in an area. Different
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