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Biological equilibrium
The tendency of the environment to restore its normal level after being disturbed.
e.g. An animal preys on another till the prey almost perishes in the environment. The predator switches to another prey & over time the first prey reproduces enough to restore its population.
Hardy & Weinberg's law:
The rate of gene distribution tends to be constant in a population therefore the characteristics in the population are constant.
The conditions that keep the genetic equilibrium of the population are:
1. The population must be large.
2. Mating is random.
3. Natural selection is absent.
4. The individuals don't migrate into the population or out of it.
5. Mutations are absent.
If these conditions are absent , the characteristics of the individuals vary , this is called genetic drift which causes the evolution of the population.
Give Reasons :
1. Variation among the individuals of a species.
Mating between organisms of different genotypes produces new phenotypes .
2. Variation in population causes evolution.
The variation allows the organisms to survive in a changing environment.
Reasons for variation among individuals of species.
3.Mating between organisms of different genotypes → new phenotypes (characteristics) appear.
4.Environmental factors → gene mutation.
5.Crossing over during meiosis.
Isolation & speciation (species formation): There're two types of speciation:
| Anagenic Speciation | Phyletic Speciation |
| 1. The indivduals are kept close therefore only small mutations occur overtime. 2. Natural selection cause the suitable mutations to be transmitted to the next generation causing the appearance of a new species. | 1. Small groups migrate away from the original group. The isolation of the new group changes it into a new species that can adapt with its environment. An example is Darwin's finches in Galapagos island which started as one species & ended into 14 species. |
Sheet 1
I-Give reasons for:
1-The bodies of both male and female contain suckers.
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2-Bilharzia worms inside the human body settle in the hepatic portal vein and its branches .
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3-The digestive system of Bilharzia worm is a simple digestive canal.
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4- The released miracidia are covered by cilia.
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5-Infection is more common among farmers .
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6-Only the 2 ends of the female appear hung outside.
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7-The life cycle of bilharzias worm includes a case of alternation of generation.
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8-Cercaria rarely infect man through the digestive system. ………………………………………………………………………………………...
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9-Cercaria must find the human within 48 hours.
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10-The embryo inside eggs secrets certain enzymes and the eggs have spines.
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11-Eggs must discharge outside the human body through urine or faeces.
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12-Female body is thinner than the male and its terminal parts are not held through the gynaecophoric groove but appear hung freely.
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II-Choose the right answer:
1-When Bilharzia eggs hatch , …………….. comes out .
(sporocyst – meracidia - cercaria)
2-Inside the snail , the meracidia developes into ……………..
(cercaria – egg - sporocyst)
3-The primary host of Bilharzia is ………………..
(man – Bulinus snail – Biomphalaria snail)
III-Draw a labeled diagram:
1-The eggs of schistoma mansoni.
2-Cercaria.
3-The female embraced with in the male.
Sheet 2
I-Write the scientific term:
| 1. Science that study the living organisms, their interaction together and with their environment, and the relation of this with man. | |
| 2. A method used by scientists in their studies and researches which has several steps. | |
| 3. A disease infects man, accompanied by bloody urine. | |
| 4. The process in which sexual and asexual reproduction occurs in two different hosts during the life cycle of Bilharzia worm. | |
| 5. A canal in the body of male Bilharzia worm where the female is embedded in. | |
| 6. A property which helps the Bilharzia's eggs to absorb water and burst. | |
| 7. A double thin membrane that separates the cytoplasm from the constituents of the nucleus. | |
| 8. The point at which two chromatids are connected together. | |
| 9. Organelles that catalyze the digestion of fats and carbohydrates because they contain a group of digestive enzymes. | |
| 10. Organelles having different colours [yellow – red – orange] and are found in the flower's petals, fruits and some leaves. | |
| 11. A lens fixed on the sliding tube of the microscope and is used to look at the object. | |
| 12. An optical instrument that magnifies samples using electromagnetic lenses. | |
| 13. Living organisms made of one cell which carries out all life functions. | |
| 14. A group of homogeneous cells that perform together specific function(s). | |
| 15. Plant tissues which have lost their power of division, arise from meristematic cells. | |
| 16. The tissue which transports food and water throughout the plant. | |
| 17. Glands with ducts that carry their secretions to the internal or external epithelial surface. | |
| 18. Ductless glands that pour their secretions directly into the blood and their secretion are known as Hormones. | |
| 19. A tissue with solid or semi – solid matrix. | |
| 20. A skeletal tissue which forms the entire skeleton of some animals like shark, and also found in the nose tip. | |
| 21. A skeletal tissue characterized by being hard due to the presence of calcium salts. | |
| 22. Thin protein filaments which gives the light bands in the striated muscles. | |
| 23. A tissue responsible for the reception of sensory impulses from sensory organs of the body and transmitting them to the brain and the spinal cord. |
II-Choose the correct answer from between brackets:
1-When Bilharzia eggs hatch …………… comes out.
(Sporocytes – Meracidiae – Fully developed worms – Cercariae)
2-When miracidium enters the snail it is transformed to …………
(cercaria – egg – sporocyst – adult worm)
3-The primary host of Bilharzia worm is ……………
(Man – Bulinus snail – Biomphalaria snail – all above)
4-The infection is transmitted to man by ……………
(Miracidium – Cercareae – Snail – Mature worm)
5-The scientist …………… made a microscope and examined different animal parts.
(Ropert Brown – Schleiden – Virchow – Leeuwenhoeck)
6-The scientist …………… discovered the nucleus of the cell.
(Robert Brown – Virchow – Schleiden – Robert hook)
7-The protoplasm of the cell is divided into two parts ……………
(nucleus and golgi body – membrane and cell walls – Cytoplasm and nucleus – mitochondria and cytoplasm)
8-The organelle responsible for connecting different cytoplasmic organelles inside the cell is the ……………
(mitochondria – ribosomes – endoplasmic reticulum – golgi body)
9-A small body found in most animal cells and has a role in the cell division ……………
(centromere – chromatide – centrosome – lysosome)
10-Lysosomes contain ……………
(digestive enzymes – respiratory enzymes – cell secretions – cellulose)
11-Chlamydomonas algae contain …………… plastids.
(cuboidal – cup-shaped – spherical – spiral)
12-…………… tissue contain green plastids and is found in the cortex of herbaceous stems.
(Sclerenchyma – Colenchyma – Chlorenchyma - Parenchyma)
13-Vascular connective tissue includes ……………
(Bones and cartilage – bones and blood – blood and lymph – blood and cartilage)
14-The matrix of the vascular connective tissue (blood) is the ……………
(lymph – blood – plasma – ossein)
15-If blood is exposed to air it ……………
(decomposes – clots – degenerates)
III-Mention the location and function of the following:
1-The ribosomes.
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2- Plasma membrane.
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3-Coarse adjustment knob in a microscope.
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4-The mirror in light microscope.
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5-The eye piece in the light microscope.
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