Life Processes Revision Material PDF

LIFE PROCESS 1. LIST THE STEPS INVOLVING PHOTOSYNTHESIS WITH REACTION (i) Absorption of light energy by chlorophyll. (ii) (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) (iii) Reduction of carbon diox...

LIFE PROCESS 1. LIST THE STEPS INVOLVING PHOTOSYNTHESIS WITH REACTION (i) Absorption of light energy by chlorophyll. (ii) (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) (iii) Reduction of carbon dioxide to carbohydrates These steps need not take place one after the other immediately. For example, desert plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day. 2. WHY IS NITROGEN REQURIED FOR PLANTS. HOW IT IS OBTAINED Nitrogen is an essential element used in the synthesis of proteins and other compounds. It is taken up in the form of inorganic nitrates or nitrites. Or it is taken up as organic compounds which have been prepared by bacteria from atmospheric nitrogen. 3. HOW IS OPENING AND CLOSING OF STOMATA REGULATED The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomata pore to open. Similarly, the pore closes if the guard cells shrink. 4. DESCRIBE HOW AMOEBA OBTAINS NUTRITION Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food-vacuole. Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out. 5. HOW DOES PHOTOSYNTHESIS TAKES PLACE IN DESERT PLANTS OR XEROPHYTES? Desert plants take up carbon dioxide at night to avoid transpiration and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day. 6. LIST THE ROLE OF A. SALIVARY AMAYLASE- breaks down starch which is a complex molecule to give simple sugar. B. PEPSIN- a protein digesting enzyme C. LIPASE- for breaking down emulsified fats. D. PANCREATIC TRYPSIN- for digesting proteins  E. BILE-The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzymes to act. Bile juice from the liver accomplishes this in addition to acting on fats. 7. WHY HERBIVORES HAVE LARGER SMALL INTESTINE The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine. 8. WHY GASTRIC GLAND HAVE MUCUS SECREATING GLANDS The mucus protects the inner lining of the stomach from the action of the acid under normal conditions. 9. DEFINE PERISTALISIS. MENTION ITS IMPORTANCE The lining of canal has muscles that contract rhythmically in order to push the food forward. These peristaltic movements occur all along the gut. It helps in pushing the food forward. 10. DESCRIBE THE ROLE OF SMALL INTESTINE VILLI The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body, where it is utilized for obtaining energy, building up new tissues and the repair of old tissues. 11. GIVE VARIOUS WAYS OF BREAKDOWN OF GLUCOSE 12. NAME TWO SPHINCTER MUSCLES IN DIGESTIVE SYSTEM AND THEIR ROLES GASTRIC SPHINCTER The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine. From the stomach, the food now enters the small intestine. ANAL SPHINCTER The exit of this waste material is regulated by the anal sphincter. 13. WHY AQUATIC ANIMALS BREATHE FASTER COMPARED TO TERESSTRIAL ANIMALS The amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. 14. DIFFERENCE BETWEEN AEROBIC AND ANAEROBIC RESPIRATION AEROBIC ANAEROBIC In presence of 02 In absence of 02 Complete breakdown Incomplete breakdown More energy is released Less energy is released End products are C02 , water Ethanol and lactic acid is and energy produced 15. WHY DOES CRAMPS OCCUR When there is a lack of oxygen in our muscle cells, another pathway for the break-down of pyruvate is taken. Here the pyruvate is converted into lactic acid which is also a three-carbon molecule. This build-up of lactic acid in our muscles during sudden activity causes cramps 16. HOW DOES EXCHANGE OF GASES TAKES PLACE IN PLANTS DURING DAY AND NIGHT TIME The direction of diffusion depends upon the environmental conditions and the requirements of the plant. At night, when there is no photosynthesis occurring, CO2 elimination is the major exchange activity going on. During the day, CO2 generated during respiration is used up for photosynthesis, hence there is no CO2 release. Instead, oxygen release is the major event at this time. 17. WHY TRANSPORTAION IS SLOW IN PLANTS Energy needs differ between different body designs. Plants do not move, and plant bodies have a large proportion of dead cells in many tissues. As a result, plants have low energy needs, and can use relatively slow transport systems. 18. HOW DOES TRANSPORTATION OF WATER AND FOOD TAKES PLACE IN PLANTS TRANSPORTATION OF WATER Xylem tissue, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil. The water which is lost through the stomata is replaced by water from the xylem vessels in the leaf. In fact, evaporation of water molecules from the cells of a leaf creates a suction which pulls water from the xylem cells of roots. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. TRANSPORTATION OF FOOD Transport of soluble products of photosynthesis is called translocation and it occurs in the part of the vascular tissue known as phloem. Besides the products of photosynthesis, the phloem transports amino acids and other substances. These substances are especially delivered to the storage organs of roots, fruits and seeds and to growing organs. The translocation of food and other substances takes place in the sieve tubes with the help of adjacent companion cells both in upward and downward directions. The translocation in phloem is achieved by utilizing energy. Material like sucrose is transferred into phloem tissue using energy from ATP 19. GIVE A FLOW PATHWAY OF BLOOD THROUGH THE DIAGRAM OF DOUBLE CIRCULATION De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it relaxes. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, relaxes, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body 20. LIST THE DIFFERENCE BETWEEN ARTERIES VEINS AND CAPILLARIES ARTERIES VEINS CAPILLARIES Thick walled Thin walled One cell thick Transport oxygenated blood Transport de-oxygenated blood Exchange of materials and except except pulmonary artery except except pulmonary vein gases between blood vessels High pressure Low pressure Connect arteries and veins Blood flows away from heart Blood flows towards heart Present near tissues Small lumen Large lumen Valves are absent Valves are present 21. DESCRIBE LYMPH AND MENTION ITS ROLE IN TRANSPORTATION Through the pores present in the walls of capillaries some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form the tissue fluid or lymph. It is similar to the plasma of blood but colorless and contains less protein. Lymph drains into lymphatic capillaries from the intercellular spaces, which join to form large lymph vessels that finally open into larger veins. Lymph carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood. 22. HOW DOES PLANT EXCRETE Plants use a variety of techniques to get rid of waste material. For example, waste material may be stored in the cell-vacuoles or as gum and resin, waste material may be stored in the cell-vacuoles and removed in the falling leaves, excreted into the surrounding soil. 23. DESCRIBE THE STRUCTURE OF NEPHRON - Coiled and tubular structure in kidney - Consists of glomerulus and capsule for ultra-filteration - Consists of renal tubule which helps in reabsorption - Consists of collecting duct which collects formed urine 24. WHAT ARE REABSORBED IN TUBULAR PART OF NEPHRON. WHAT CONSTITUES URINE. Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube. Urine consists of nitrogenous waste , urea, uric acid , salts and water. 25. DRAW A NEAT LABELLED DIAGRAM OF EXCRETORY SYSTEM IN HUMANS Kidney ureter urinary bladder urethra 26. HOW IS URINE REGULATED IN HUMANS The amount of water re-absorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. More water in body - less reabsorption of water Less water in body - more reabsorption of water The bladder is muscular, so it is under nervous control, as we have discussed elsewhere. As a result, we can usually control the urge to urinate. 27. LIST THE DIFFERENCE BETWEEN RENAL ARTERY AND RENAL VEIN Renal artery Renal vein Carries oxygenated blood to Carries de oxygenated blood kidney from kidney Consists of nitrogenous waste No nitrogenous waste 28. HOW IS LEAF STRUCTURE HELPING IN MAXIMUM PHOTOSYNTHESIS -Larger lamina surface -More air spaces in between cells for easy diffusion of gases -More cells containing chloroplast that help in photosynthesis -Mid rib helps in transport of water and food -Stomata in epidermis helps in exchange of gases. 29. LIST THE TYPES OF HETEROTROPHIC NUTION WITH EXAMPLES. Saprophytic nutrition- organisms break-down the food material outside the body and then absorb it. Examples are fungi like bread moulds, yeast and mushrooms. Holozoic nutrition- Organisms take in whole material and break it down inside their bodies Parasitic nutrition- organisms derive nutrition from plants or animals without killing them. Examples are cuscuta (amar-bel), ticks, lice, leeches and tape-worms. 30. WHY IS MAMMAL AND BIRDS HAVE 4 CHAMBERED HEART The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature. 31. WHY IS RESIDUAL VOLUME NEEDED? The lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released. 32. WHY IS RESPIRATORY PIGMENT NEEDED? Respiratory pigments take up oxygen from the air in the lungs and carry it to tissues which are deficient in oxygen before releasing it. In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. This pigment is present in the red blood corpuscles. Carbon dioxide is more soluble in water than oxygen is and hence is mostly transported in the dissolved form in our blood. 33. WHY ATP IS CALLED ENERGY CURRENCY? The energy released during cellular respiration is immediately used to synthesise a molecule called ATP which is used to fuel all other activities in the cell. In these processes, ATP is broken down giving rise to a fixed amount of energy which can drive the endothermic reactions taking place in the cell. 34. HOW DOES CIRCULATION HAPPEN IN FISHES, AMPHIBIANS AND REPTILES. In animals that do not use energy for this purpose, the body temperature depends on the temperature in the environment. Such animals, like amphibians or many reptiles have three- chambered hearts, and tolerate some mixing of the oxygenated and de-oxygenated blood streams. Fishes, on the other hand, have only two chambers to their hearts, and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body.  How do Organisms Reproduce  Reproduction is the process by which living organisms produce new individuals of the same species  Reproduction is necessary for the survival and increase in the population of a species. If organisms do not reproduce, their population decreases and species will become extinct.  Significance of Reproduction: It allows continuity of of a species generation after generation. 2.It plays an important role in evolution by transmitting favourable variations from one generation to another generation DNA copying  DNA copying or also called as DNA replication is a process of producing two identical copies from one original DNA molecule.  DNA copying is otherwise known as DNA replication which is the process of producing 2 identical copies of DNA from one original DNA molecule during cell division. DNA copying is important 1. it generates variation during sexual reproduction which leads to evolution. 2. DNA copying helps in transfer of information or characters from the parents to the offsprings  The importance of variation :- DNA copying during reproduction is important for maintaining the body designs of different organisms to survive in the existing environment. But the environment is constantly changing due to changes in temperature, climate, water levels etc. If organisms cannot adjust themselves to the changes in the environment then their species will become extinct. If there are variations in some individuals of a species they may be able to survive the changes in the environment. So variations in species is necessary for the survival of different species and for the evolution of new species Recall Question based on the concept: 1.Define reproduction 2.Explain the significance of reproduction in living organisms. 3.what is DNA copying? List out the important of DNA copying 4. When a cell reproduces, what happens to its DNA? 5.Variations” are seen in the organisms. State the two main causes of variation 6. Define variation in relation to a species. Why is variation beneficial to the species 7. Define reproduction. How does it help in providing stability to the population of species Types of reproduction :- There are two main types of reproduction in living organisms. They are asexual reproduction and sexual reproduction.  Asexual reproduction: - is reproduction in which new individuals are produced from a single parent.  Sexual reproduction: - is reproduction in which two individuals are involved to produce a new individual. Asexual reproduction is of different types. They are:- fission, budding, regeneration, fragmentation, spore formation, vegetative propagation etc.  i) Fission :- Fission is an asexual reproduction by which a unicellular organism splits into two or more new individuals. Fission is of two types. They are binary fission and multiple fission. i) Binary fission :- In this method an organism divides and forms two individuals. First the nucleus divides and forms two nuclei. Then the cytoplasm divides and forms two daughter cells. Eg:- Amoeba(division can occur in any plane), Leishmania. (cause Kala-azar) binary fission occurs in a definite orientation Binary fission Leishmania, In Leishmania, the splitting of parent cell during fission (or cell division) takes place in a definite plane (longitudinally) with respect to flagellum at its end 1. Nuclear division is followed by the appearance of a constriction in the cell membrane. 2. The membrane then grows inward from near the middle of the dividing cell. 3. Cytoplasm separates into two equal parts, each with one nucleus. 4. The two-daughter cell may separate from each other and behave as two independent organisms. Multiple fission :- In this method one organism splits into many daughter cells. Eg. Plasmodium Multiple fission in Plasmodium: It is an asexual mode of reproduction in organisms. Here, In this process the organism produces a thick outer covering called cyst around itself. Within the cyst, the parent cell produces multiple daughter nuclei by repeated divisions which is surrounded by cytoplasm. During favorable conditions the cyst breaks open, releasing the daughter cells. Each daughter cells grows into a new organism 2. BUDDING Budding is an asexual method of reproduction. In budding, a small part of the body of the parent organism grows out as a ‘bud’ which then detaches and becomes a new organism. The asexual reproduction by budding is observed in Hydra and yeast. BIDDING IN HYDRA 1.Hydra reproduces by the process of budding (by using its regenerative cells). This happens as follows : In Hydra, first a small outgrowth called ‘bud’ is formed on the side of its body by the repeated mitotic divisions of its cells 2.This bud then grows gradually to form a small Hydra by developing a mouth and tentacles 3.And finally the tiny new Hydra detaches itself from the body of parent Hydra and lives as a separate organism BIDDING IN YEAST 1.Yeast is tiny, unicellular, non-green plant, Yeast reproduces by budding. 2.In yeast, first a bud appears The nucleus of parent yeast cell then divides into two parts and one part of the nucleus moves into the bud on the outside of the cell wall. Ultimately, the bud separates off from the parent yeast cell and forms a new yeast cell. 3.The budding in yeast, however, often takes place so fast that the first buds start forming their own buds and all of them remain attached to the parent yeast cell forming a chain of yeast cells. iii) Regeneration , If the individual is somehow cut or broken up into many pieces, many of these pieces grow into separate individuals. Or complete organism eg Hydra and Planaria Regeneration in hydra- Regeneration is carried out by specialised cells. These cells proliferate and make large numbers of cells. From this mass of cells, different cells undergo changes to become various cell types and tissues. These changes take place in an organised sequence referred to as development. iv) Fragmentation :- In this method the body of a simple multicellular organism breaks up into smaller pieces on maturation and each fragment develops into new individuals. Eg :- Spirogyra v) Spore formation :- In spore formation, the parent plant produces hundreds of microscopic reproductive units called ‘spores. The common bread mould plant consists of fine, thread- like projections called hyphae( non-reproductive part ) and thin stems having knob- like structures called sporangia Each knob- like structure (or sporangium) contains hundreds of minute spores enclosed in a spore case. (vi) Vegetative propagation: New plants are produced from the vegetative parts of the plant like root, stem or leaf For example, leaves of a Bryophyllum plant have special type of buds in their margins (or edges) These buds may get detached from the leaves, fall to the ground and then grow to produce new Bryophyllum plants. Potato tuber can be used for the vegetative reproduction of potato plants. Each potato tuber can produce more than one plant. A potato tuber has many buds (called eyes) on its body These buds act as organs for vegetative reproduction. When a potato tuber is planted in the soil, then the various buds of the potato tuber start growing to form new potato plants.( There are two types of tubers : stem tubers and root tubers. Potato is a stem tuber whereas sweet potato is a root tuber) Importance of Vegetative Propagation  Plants can bear flowers and fruits earlier.  Plants which have lost the ability to produce viable seeds can also reproduce by vegetative propagation.  All plants are genetically almost similar to the parent plant..Disadvantages of vegetative propagation Induces overcrowding No genetic variation. New varieties are neither introduced nor undesirable characters removed. Tissue Culture: The technique of developing new plants from a cell or tissue in a nutrient medium under aseptic conditions. The cell or tissue is placed in a nutrient medium where it forms a mass of cells called callus. This callus is then transferred to another nutrient medium where it differentiates and forms a new plant. Advantages of Tissue Culture 1. Tissue culture is a very fast technique. Thousands of plantlets can be produced in a few weeks’ time from a small amount of plant tissue. 2. The new plants produced by tissue culture are disease free. Advantages of Asexual reproduction: 1. Plants takes less time to grow. 2. It also helps in the propagation of plants which do not produce seeds like rose, jasmine banana or produce seed with prolonged period of dormancy. 3. It helps to preserve parental characters. Disadvantages of Asexual reproduction: 1. There is no genetic variation, so there is less adaptability to the environment. 2. The disease of the parent plants get transferred to the offspring. 3. New characters can neither be introduced nor undesirable characters be eliminated Recall Question based on the concept 1. What is vegetative propagation? List two advantages and two disadvantages of vegetative propagation 2. Explain the term “Regeneration” as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like Hydra 3. What is fission? explain binary fission in amoeba and Leishmania, 4. Explain multiple fission in plasmodium 5. Explain budding in Hydra and yeast 6. Define and explain the fragmentation Spirogyra 7. Name and explain the method by which Rhizopus reproduces 8. Explain regeneration in planaria 9. Identify the asexual method of reproduction in each of the following organisms: (i) Rose (ii) Yeast (iii) Planaria b. What is fragmentation? Name a multicellular organism which reproduces by this method 10.what are the advantage and disadvantage of asexual reproduction 11.a. How will an organism be benefitted if it reproduces through spores? b. Mention the two asexual methods by which hydra can reproduce. Explain briefly any one such method. Sexual Reproduction: The mode of reproduction that takes place with the involvement of two individuals of two different sexes i.e. male and female. Male and female gametes fuse to form a zygote that grows into a new organism. Significance/advantages of Sexual Reproduction: Sexual reproduction involves DNA as well as cellular apparatus of two different organisms which promotes diversity of characters in the offspring. It results in a new combination of genes which increases the chances of genetic variations. Sexual reproduction results in the origin of new species. Sexual reproduction involves reduction of the DNA matter to half so that the zygote formed after fusion has the same amount of DNA as the parents. Limitation of Sexual Reproduction: Sexual reproduction involves the process of combining DNA from two different organisms which may bring some undesirable features also Sexual reproduction in flowering plants: -. The reproductive parts are present in the flower,.angiosperms are commonly known as flowering plants. The flowering plants reproduce by ‘sexual reproduction’ method.. The function of a flower is to make male and female gametes and to ensure that fertilisation will take place to make new seeds for the reproduction of plant PARTS AND FUNCTION OF FLOWER PARTS FUNCTIONS Sepals(CALYX) green structures that protect the inner parts when the flower is in bud stage. Petals(COROLLA) colourful and attract the insects for pollination Receptacle. The base of a flower to which all the parts of a flower are attached Stamens(Androecium) Stamens are male reproductive parts and produce pollen grains that contain male gametes. Each stamen has two parts a filament and an anther Filament Stalk of the stamen that hold up the anther Anther Contain pollen sac in which pollen grain are formed, pollen contain male sex cell carpel or The female reproductive part of flower, which are made up stigma pistil(Gynoecium) style and ovary Stigma Stigma which is top sticky part and receives pollen grains during pollination Style Style which is the middle long part, which link stigma and ovary, through which pollen tube grows ovary ovary which is the swollen part and contains ovules. Each ovule has an egg cell i.e. female gamete.    Pollination: The process of transfer of pollen grains from an anther to the stigma of the flower is pollination. Two types of pollination are:  (i) Self-pollination: The transfer of pollen grains from the anther to the stigma of the same flower or another flower of the same plant.  (ii) Cross-pollination: The transfer of pollen grains from the anther to the stigma of another flower or another flower of a different plant of the same species. It generally takes place with the help of some agents like insects, birds, wind and water. Fertilization:  Pollen grains land on the stigma of the ovary. Pollen tubes grow out of the pollen grains, travel through the style and reach the ovary, through the style. Each ovule has two polar nuclei and a female germ cell (egg). Pollen tube releases two male germ cells inside the ovule- One of them fuses with female germ cell and forms a zygote which grows into the baby plant i.e. embryo, the fusion is known as syngamy. The other male germ cell fuses with two polar nuclei, the process is known as triple fusion. So in flowering plants, two fusions take place during fertilisation. It is called double fertilisation Post-fertilisation changes: ▪ After fertilisation the following changes takes place in the flower. Zygote divides several times and forms an embryo inside the ovule. The ovule develops a tough coat and changes into the seed. The ovary grows rapidly and ripens to form a fruit. Petals, sepals, stamens, style and stigma shrivel and fall off. Advantages of Seed: The advantage of seed is that it protects the future plant i.e. embryo. Seed has parts: Cotyledons store food for the future plant. Embryo has two parts: plumule and radicle. Plumule develops into shoot and radicle develops into root  The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination Recall Question based on the concept 1. Identify the Parts and write the function of flower 2. Explain Male and female reproductive part of the flower 3. What is pollination? Explain its significance. 4. Explain the process of fertilization in flowers with the diagram. Name the parts of flower that develop after fertilization into (i) seed (ii) fruit 5. Explain post fertilization in flower 6. Define germination? Parts and function of dicot seed Reproduction in Human Being: Human beings show sexual reproduction. Male parent produces male gametes called sperms. Female parent produces female gametes called ova. Sperms have tail and are therefore, motile. They are produced in large numbers in the testes. Ovum is bigger, non-motile and only one ovary produces one ovum in one month. There is no food stored in the sperms whereas ova contain stored food. Both the gametes are microscopic unicellular and have half the number of chromosomes as compared to the body cells. Human beings become reproductively active from the onset of puberty. Puberty is the period during adolescence when the rate of general body growth begins to slow down and reproductive tissues begin to mature. Onset of puberty in human males is between 11 to 13 yrs of age, while in human females is between 10 to 12 yrs. of age. SEXUAL MATURITY IN HUMAN BEING: various changes takes place in human body at the time of sexual maturity:- Changes common in both boys and girls:- 1) Thick hair growth in armpits & genital area between the thigh (also called Pubic region). 2) Thinner hair on legs, arms and faces. 3) Oily skin and appearance of pimples Changes different in boys and girls: In Girls: 1) Breast size begin to increase. 2) Darkening of the nipple skin. 3) Start of menstruation. In Boys: 1) Thick facial hair growth. 2) Voice begin to crack. 3)Penis occasionally begin to erect and enlarged followed by night flow. PUBERTY: It is the age at which the sex hormone or gametes begin to be produced and the boy and girls becomes sexually mature. List four steps in sexual reproduction. Write two of its advantages Male Reproductive System: Male reproductive system consists of the following components  .  MALE REPRODUCTIVE SYSTEM PARTS AND THEIR FUNCTION TESTES Testes are the primary reproductive organs in man (or males), Functions of testes  To produce male gametes i.e. the sperms.  To produce a male reproductive hormone called testosterone which is responsible for producing sperms as well as secondary sexual characteristics in males. scrotum One pair of testes are present in a bag-like structure called scrotum which lies outside the abdominal cavity, the temperature in the scrotum is 2-3 times lower than the body temperature which is suitable for the production of sperms. Hence testes is present outside the abdominal cavity Epididymis sperms get stored temporarily in epididymis  Vas a long tube, which connect the epididymis and urethra. vas deferens (or transports mature sperm to your urethra before ejaculation sperm duct) Urethra uUrethra male urethra common passage for both urine and semen Seminal vesicles- it is an accessory reproductive gland present in males. It produces nourishing fluid which makes part of semen and help in transportation of sperm Prostate gland- It secretes an alkaline fluid into the semen, which neutralizes acid in females reproductive track and help in sperm motility Cowper’s gland produce an alkaline secretion containing mucus that lubricates the urethra of the penis. penis The function of the penis is to deliver semen into the vagina during sexual intercourse. FEMALE REPRODUCTIVE SYSTEM SEXUAL REPRODUCTION IN HUMAN BEING: The sperm is introduced inside the female vagina through the penis by the process of copulation or mating. Fertilization occurs in the fallopian tube. Sperms are highly active & mobile which move up through cervix into the uterus and then pass into the fallopian tubes. In the fallopian tube only one sperm fuses the ovum to form zygote. This is called fertilization The embryo development of the zygote starts immediately in the fallopian tube and pregnancy starts while menstruation stops. The embryo moves down to reach the uterus. The embryo gets embedded in the thick inner lining of the uterus (process is called Implantation) The time period from the development of fetus inside the uterus till birth is called Gestation period. It is approximately 9 months in human. At the end of gestation period the female give birth of the fully developed fetus (The act of giving birth is termed as Parturition Placenta: The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. This is a disc which is embedded in the uterine wall. It contains villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi. This provides a large surface area for glucose and oxygen to pass from the mother to the embryo. The developing embryo will also generate waste substances. which can be removed by transferring them into the mother’s blood through the placenta Menstrual Cycle: Represent cyclic changes in the reproductive system of female. It begins with menstruation. Menstruation: The breakdown and removal of the inner thick and soft lining of the uterus along with blood vessels in the form of vaginal bleeding is called menstruation / menstrual flow. First menstruation which occurs at the age of 11-12 years is called MONARCHE. The last menstruation which occurs at the age of 45 years marks the end of the reproductive period is called MENOPAUSE REPRODUCTIVE HEALTH: is all those aspects of general health which help a person to lead a normal, safe and satisfying life. STDs(Sexually Transmitted Disease):- are the disease which are spread by sexual contact from an infected person to a healthy person. They are caused by various microorganisms They can be caused by bacteria for example; syphilis, gonorrhoea; and caused by a virus for example; HIV-AIDS, warts etc. The transmission of these diseases can be avoided by using birth control measures such as wearing a condom during the sexual act AIDS(Acquired Immune Deficiency Syndrome) :- It is caused by virus called HIV (Human Immune Virus) which suppresses the body's immune system and thereby making it susceptible to any disease. Modes of transmission of aids: By having Sexual contact with an infected person. By the transfusion of blood from an infected person. Through infected needles used for injection. Through the placenta from the mother to child during pregnancy BIRTH CONTROL METHODS The prevention of pregnancy in women (by preventing fertilisation) is called contraception. And any device or chemical (drug) which prevents pregnancy in woman is called a contraceptive. All the birth control methods can be broadly divided into three categories : 1. Barrier methods, 2. Chemical methods, and 3. Surgical method Mechanical methods: These are used to prevent the passage of semen to the follopian tube : (i) Use of condoms: Condoms are thin rubber tubes worn over the penis before sexual intercourse. The semen gets collected in this and is not discharged into the vagina. (ii) Diaphragm: It is a thin rubber fixed over a flexible metal ring which is fitted over the cervix in a woman’s body by a doctor. (iii) Intra Uterine Contraceptive Device (IUCD) or loop: It is inserted in the uterus and its insertion causes certain secretion which prevents the implantation of the embryo in the uterine wall. Both methods (ii) and (iii) cause side effects Chemical methods  Use of spermicides: These are strong sperm-killing chemicals available in the form of creams, jellies etc. which are injected into the vagina just before copulation.  Oral contraceptive pills: These are hormonal pills which prevent ovulation but do not stop menstruation. Surgical methods  Vasectomy: It involves cutting and ligating the vas deferens in males.  Tubectomy: It involves cutting and ligating Reproductive organs the fallopian tubes in females.  Medical termination of pregnancy (MTP) or abortions is carried out to eliminate the developing embryo. This practice can, however, be misused to carry out female foeticide which involves the killing of the female foetus. It should be avoided at all cost as it disturbs the male- female ratio in a population. Recall Question based on the concept 1. What are sexually transmitted diseases? Name any one which is caused by bacteria and one caused by viral infection. b. Mention any two methods to avoid such diseases 2. The chromosome number of the sexually reproducing parents and their offsprings is the same”. Justify the statement. 3. What are chromosomes? Explain how in sexually reproducing organisms, the number of chromosomes in the progeny is maintained 4. List four categories of contraceptive methods. State in brief two advantages of adopting such preventive methods 5. What is placenta? Describe its structure. State its functions in case of a pregnant human female 6.Identify the parts and write the function of male reproductive system 7.Identify the parts and write the function of female reproductive system 9.Explain what will happen if egg is not fertilization 10.list out any two secondary sex character common and different in both boys and girls 11.Important processes definition need to be practiced in female fertilization rocesses ACTIVITY NEED TO BE PRACTICED S.N. Contents 1 Activity 7.1 Science –Budding in yeast 2 Activity 7.2 Science-Rhizopus -2022-23 3 Activity 7.3 Science-Binary fission in Amoeba (2019) 4 Activity 7.4 Science—Fragmentation in spirogyra(2017) 5 Activity 7.5 Science –vegetative propagation(2022- 23) 6 Activity 7.6 Science-vegetative propagation (2022- 23) 7 Activity 7.7 Science –seed germination(2019- 2020,2022-23) DIAGRAM NEED TO BE PRACTICED 1.Binary fission in Amoeba 2.Binary fission in Leishmania 3.Multiple fission in plasmodium 4.Regeneration in planaria 5.Budding in yeast 6.Budding in hydra 7.Vegetative propagation-Bryophyllum 8.Spore formation in Rhizopus 9.LS of Flower 10.Germination of pollen on Stigma 11.Dicot seed diagram 12. Male reproductive system 13.Female reproductive system Differentiate between the following a. Pollen tube and Style b. Fission of Amoeba and Plasmodium c. Fragmentation and regeneration d. Bud of Hydra and bud of Bryophyllum e. Vegetative propagation and spore formation f. ovary and testis g. sexual and asexual types h. unisexual and bisexual flowers i. Fertilization and germination j. Fission in Amoeba and Plasmodium. k. Binary fission and Fragmentation l. male and a female gamete m. pollen grain and ovule n. pollination and fertilization. o. plumule and radicle p. Binary fission and multiple fission q. Sperm and ovum r. Self-pollination and cross pollination. s. Style and filament t. Zygote and embryo u. Vasectomy and Tubectomy CONTROL AND COORDINATION  In animals, the nervous system and hormonal system are responsible for control and coordination.  Nervous system- is composed of specialized tissues, called nervous tissue.  The nerve cell or neuron is the functional unit of the nervous system  Functions of the nervous system 1.Nervous system receives information from the environment 2. To receive the information from the various body. 3.To act according to through muscles and glands. Neuron:(Draw the structure the neuron and label the parts) A neuron is the structural and functional unit of the nervous system. They have three distinct parts, including a cell body, axon, and dendrites. Cell body- Neuron cell body is also called as cyton.It has abundant cytoplasm, nucleus, and mitochondria.  Dendrites-These are branch-like structures where the information is acquired  Axon-The part of the neuron through which information travels as an electrical impulse is known as the axon of the neuron. Axons mostly are covered with Myelin Sheath which increases the speed of signal transmission. Synapse- Synapse is the functional gap between the terminal branches of the axon of one neuron and dendrite of another neuron.. Here, electrical signal is converted into chemical signal for onward transmission. Neuromuscular Junction (NMJ): NMJ is the point where a muscle fibre comes in contact with a motor neuron carrying nerve impulse from the control nervous system.  Stimuli-The changes in the environment to which living organisms response are called stimuli eg- heat, sound, taste, touch ,pressure etc  RECEPTORS-: it is a cell or group of cells specialized to detect particular stimulus and to initiate the transmission of impulse via the sensory nerves which are located in the sense organ Recall question 1. All information for our environment is detected by specialized tips of some nerve cells. Write the name given to such tips and also mention where are they located? 2. State the function of: gustatory receptors olfactory receptors 3. 3.What is synapse 4. 4. Define neuron. Name the parts of the neuron where: information is acquired. impulse must be converted into a chemical signal for onward transmission 5.. Draw and label a neuron. Explain how it carries messages 6. Identify the parts neuromuscular junction .  REFLEX ACTION: it is the intermediate (or instant) involuntary and unconscious response to stimuli. It is controlled by CNS (except the Cerebrum) mainly by spinal cord.  REFLEX ARC- The pathway through which nerve impulses pass during reflex action is called reflex arc.  Draw the diagram of reflex arc(label all the parts) Path way of reflex action- . NERVE IMPULSE: - it is the information in the form of chemical and electrical signals passing through neurons  TYPES OF NERVES CELLS: nerve cells are of Three types on the basis of direction of conduction of nerve impulse:-  Sensory Nerve: Conduct nerve impulse from receptors towards the central nervous system.(brain and spinal cord)  Motor Nerve: Conduct nerve impulse away from central nervous to the Organs (effectors).  Mixed(relay) nerve: Conduct nerve impulse both towards & away from the CNS.  Effector-A muscle, gland or an organ capable of responding to a stimulus, especially a nerve impules.  Response: It is the final reaction after the reflex action. Three types of responses:  VOLUNTARY ACTION: The actions which are in control of our will i.e. these actions need thinking and are preformed knowingly i.e. are controlled by conscious thought.  E.g. - Speaking to a friend, writing a letter etc  INVOLUNTARY ACTION: these are not under the control of the will of an individual and are automatic response to a stimulus. e.g. - Touching of a hot plate unknowingly Recall question 1. Define ‘reflex action’ 2. Write two differences between the response of the plants and response of the animals to stimuli? 3. Trace the sequences of events through a reflex arc which occur when a bright light is focused on your eyes a.What is reflex arc? 4. what are the components of reflex arc? 5. Differentiate between sensory neurons and motor neurons 6. “Reflex arcs continue to be more efficient for quick responses”. Justify this statement giving reason 7.. Draw a flow chart showing the sequence of events which occur during sneezing  Human Nervous System 1.Human nervous system consists of two parts, Central nervous system (CNS) and Peripheral nervous system (PNS).  2.Central nervous system consists of Brain and Spinal Cord. 3.Peripheral nervous system consists of Cranial Nerves (12 pair) which arise from the brain and Spinal Nerves (31 pair)which arise from the Spinal cord. Human Brain (Draw neat labelled diagram of Human brain) Brain is the main coordinating centre of the body. It has three major parts: (i) Fore-brain (ii) Mid-brain  (iii) Hind-brain Cerebrum Largest part of the body,, center for intelligence,thinking,memory and voluntary action Hypothalamus Control body temperature,urge for eating and drinking(hunger) Thalamus Center for sensory and motor signaling MIDBRAIN Controls involuntary actions such as change in pupil size and reflex movements of head, neck and trunk. HIND BRAIN cerebellum Controls posture and balance of the body Precision of voluntary actions. Example: picking pen Pons Regulates respiration medulla Control all involuntary actions including blood pressure,salivation,and vomiting Protection of Brain and Spinal Cord  Protection of Brain: Brain is protected by a fluid filled balloon which acts as shock absorber and is enclosed in cranium (skull or brain box).  Protection of Spinal Cord: Spinal cord is enclosed in vertebral column.  Cerebrospinal fluid- The fluid present between membranes of brain, It protects the brain from shocks and injuries Recall question 1. List two body functions that will be affected if cerebellum gets damaged 2. Give the scientific names of the following regions of the human brain: Region for sight. Region which controls salivation 3. a.Give the functions of cerebellum (any two). b.Name the components of central nervous system 4.‘Brain and spinal cord are two vital organs of our body’. How is our body designed to protect them 5.a. Name the part of brain which controls (1) voluntary action, (2) involuntary action. b.What is the significance of the peripheral nervous system? Name the components of this nervous system and distinguish between the origin of the two. 6. Draw a labelled diagram of human brain. Discuss functions of cerebrum, cerebellum and medulla. or Draw and describe the role of various parts of human brain Control and Coordination in Plants Movement in plants: Plants do not have a nervous system. Plants use chemical means for control and co- ordination. Many plant hormones are responsible for various kinds of movements in plants. There are two main types of movement in plants: 1}Tropic movement 2} Nastic movement Movement need to be practice along with the definition, diagram in activity based formate 7. Tropic Movement 8. Geotropic movement 9. Phototropic Movement 10. Hydrotropic Movement 11. Thigmotropic Movement 12. Chemotropic Movement 13. Nastic Movement Recall question 1.Describe an activity to illustrate the phenomenon of phototropism and explain why does this occur(5mark) 2. (a) What is phototropism and geotropism? With labelled diagrams describe an activity to show that light and gravity change the direction that plant part grows in. (b) Mention the role of each of the following plant hormones: (i) Auxin (ii) Abscisic acid. 3. Tendrils encircle or coil around the object in contact with it. Elaborate 4. What is meant by hydrotropism? Give an example 5. Define ‘Chemotropism’. Give one example of chemotropism 6. What type of movement is shown by mimosa plant leaves when touched with a finger? Plant hormones: Plant hormones are chemicals which help to co-ordinate growth, development and responses to the environment. They are called phytohormone. There are five main types of plant hormones. Auxin which promotes cell elongation Gibberellins which promotes cell differentiation and growth of stem Cytokinin which promotes cell division and the opening of stomata. Abscisic Acid promotes wilting and falling of leaves. Ethylene It helps in flowering and ripening of fruit Recall question 1.what is plant hormone? List out all the plant hormones write their function 2. Illustrate with the help of a diagram, the effect of auxins in different parts of a plant 3. State how concentration of auxins stimulates the cells to grow longer on the side of shoot which is away from light 4. a. Identify the phytohormone used by plants while performing the following functions: a. Cell division in shoot tip. b. Inhibiting growth on approach of unfavorable conditions. b. List in tabular form two differences between the movement in ‘touch me not’ plant and movement of shoot towards light 5.Name the hormone synthesized at the shoot tips. How does it help the plant to respond to  light? Endocrine System: The endocrine system is composed of several endocrine glands. A ductless gland is called endocrine gland. Endocrine gland secretes its product directly into the bloodstream. Hormones are produced in the endocrine glands Hormones-The chemical substance that are produced by endocrine gland. Endocrine Gland Location Hormones Functions Deficiency Produced Hypothalamus brain Releasing and It regulates the secretion Hypothalamic inhibiting of hormones produced disease hormones by the pituitary gland Pituitary gland At the base of Growth GH stimulates growth in Deficiency leads (also known as the the brain hormone (GH) all organ and to dwarfism and master gland development of the body excess leads to gigantism Pineal gland Dorsal side of melatonin Maintain sleep-wake Mood forebrain cycle disorders,dementia Thyroid Gland Neck Thyroxine Regulates Deficiency leads carbohydrate,protein,and to goiter fat metabolism and best blance for growth Thymus gland Between the thymosins Development of the Immunity become lungs immune system weak  Adrenal gland Above Adrenalin Prepares the body for Excess of kidneys emergency situations hormones speed and hence is also called up the heartbeat ‘Fight and flight’ and blood pressure hormone. Regulate heartbeat, breathing rate Pancreas Near stomach Insulin Lower the blood sugar Diabetes mellitus level glucagon Raises blood sugar level Testis (male) In Scrotum Testosterone Sperm production, Decrease in development of muscle mass, with secondary sexual increase in body characters during fat and weight puberty in male gain Ovary (female) Near uterus Oestrogen Egg production, Fertility disorders, development of menstrual disorder secondary sexual characters during puberty. ovary Near uterus progesterone Supports pregnancy and Difficulty in milk secretion conceiving Iodized salt is necessary because: Iodine mineral is essential part of thyroxine hormone so it is important that we must consume iodized salt as in turn it is essential for thyroid gland as it controls carbohydrate, proteins and fat metabolism for best balance of growth deficiency of iodine might cause disease called goiter Diabetes: Cause: It is due to deficiency of insulin hormone secreted by pancreas that is responsible to lower/control the blood sugar levels. Treatment: Patients have to internally administer injections of insulin hormone which helps in regulating blood-sugar level In case of flight or fight reaction to an emergency situation, Adrenal glands → release adrenaline into blood → which acts on heart and other tissues → causes faster heart beat → more oxygen to muscles → reduced blood supply to digestive system and skin → diversion of blood to skeletal muscles → increase in breathing rate feedback Mechanism → The excess or deficiency of hormones has a harmful effect on our body. Feedback mechanism makes sure that hormones should be secreted in precise quantity and at right time. Example: Feedback mechanism to control the sugar level in blood is as follows: Recall question 1.Identify the different type of gland mention the hormone released and write their function 2.What are hormones? Name the hormone produced by thyroid gland and state its function 3.a. Name the hormone which is injected to a diabetic patient. b.Why should we use iodised salt in our diet? c.If iodine is insufficient in one’s diet, what might be the deficiency disease and its symptoms 4. a. Name the diseases by which a person is likely to suffer due to the deficiency of: (i) iodine (ii) insulin b. How the timing of secretion and amount of hormone secretion are regulated in human system. Explain with example 5. Which hormone is secreted during emergency situations like anger or excitement? How does it help the human body to handle such situations? or How does our body respond when adrenaline is secreted in to the blood? 6.Answer the following: a. Name the endocrine gland associated with brain. b. Which gland secretes digestive enzymes as well as hormone? c. Name the endocrine gland associated with kidneys. d. Which endocrine gland is present in males but not in females? e. Which hormone is responsible for changes in females during puberty? f. Iodine is necessary for the synthesis of which hormone. 7.The two glands A and B which occur in pairs are present in endocrine system. The pair of glands A is found only in females whereas the pair of glands B occur only in males. The gland A make and secrete hormone C whereas gland B make and secrete hormone E. In addition to hormone, gland A makes gamete F whereas gland B makes gamete G. a. What are glands A and B? b. Name the hormone C and E c. Name the gamete F and G. 8. Give reasons: a. Pituitary is often termed as master endocrine gland. b. Pancreas helps in digestion and also regulates blood sugar level. c. Adrenals are known as glands of emergency 9. a. An old man is advised by his doctor to take less sugar in his diet. Name the disease from which the man is suffering. Mention the hormone due to imbalance of which he is suffering from this disease. Which endocrine gland secretes this hormone? b. Name the endocrine gland which secretes growth hormone. What will be its effect on a person if there is: (i) Deficiency of growth hormones (ii) Excess secretion of growth hormones  HEREDITY CONCEPT IN CAPSUL FORM (PRACTICE ALL THIS DEFINIATION) Heredity-Heredity refers to the transmission of characters from one generation to the next generation. Or transmission of characters from the parents to their offspring’s. Variation-The difference in the characters among the individual of a species are called variations Genetics- The branch of biology deals with the study of heredity and variation Genotype – is defined as the genetic constitution of an individual for any particular character or trait or It refers to the genetic makeup of an individual. For example- a tall plant is represented by TT or Tt , short plant is represented by tt Phenotype – is defined as physical appearance of an individual for any particular Trait. Or It refers to the physical appearance of the organism. For example- TT-Tall, Tt-Tall, tt-short dominant gene-. The gene which can expresses itself even in the presence of its alternate gene. The dominant gene is represented by a capital letter.eg-TT ,Tt Recessive gene -The gene which expresses itself only when it is present in homozygous condition. Recessive gene is represented by a small letter.eg-tt Alleles- An allele is an alternative form of a gene. It is located in a specific location on a certain chromosome. Homozygous: - it is a word that refers to a particular gene that has identical alleles on both homologous chromosomes. Heterozygous: - A diploid organism is said to be heterozygous at a gene when its cells contain two different alleles of a gene. GENE-A gene is the basic physical and functional unit of heredity. Genes are made up of DNA and each chromosome contains many genes DNA-Deoxyribonucleic acid (abbreviated DNA) is the molecule that carries genetic information for the development and functioning of an organism RECALL QUESTION 1. Give the respective scientific terms used for studying: a. the mechanism by which variations are created and inherited, and b. the development of new type of organisms from the existing ones. 2. a. Write full form of DNA. b. Why are variations essential for the species? 3.. a. Why do we say that homozygous plants produce pure progeny? b. Define heterozygous 4.. Give differences between: a. Heredity and variations. b. Dominant and recessive traits. Accumulation of variation during Reproduction:  Reproduction is a process that gives rise to new offspring that are similar to the parents but with some variations between them due to the process of DNA copying. Variation in Asexual Reproduction: In case of asexual reproduction single parent is involved in the process so the trasfer of genetic material is from single parent only. Due to this reason not much variation is seen in these types of offspring; only little changes can be seen because of inaccuracies happening during DNA copying mechanism. Example: Very minor variation can be seen in case of fruits and vegetables. B. Variation in Sexual Reproduction: In case of sexual reproduction two parents are involved as there is fusion of gametes from two different individuals. Due to which their genes get mixed up and causes maximum number of variations in their offspring and due to this offspring looks different from their parents. This variation which is accumulated in an offspring is passed from generation to generation and this maintains genetic continuity of an organism. These variations are noticeable from generation to generation. Example: Human being offspring show accumulation of variation.. Importance of Variations As variation is a complex process by which we can determine similarities and dissimilarities present in an individual offspring. There are so many advantages of variations. Some of them are listed below:  Evolution occurs because of variation in an individual.  Variations lead to the base of healthy genes from generation after generation.  It is easy to adapt in any condition with the help of variations.  It is helpful in the selection process of the best trait. For example, the bacteria that can tolerate higher temperatures would survive the heat waves RECALL QUESTION  1.. Give five points to show the significance of variations 2.. “Only variations that confer an advantage of an individual organism will survive in a population”. Comment 3.. What is the importance of DNA copying in reproduction? Why is variation beneficial to the species but not necessary for the individual? Explain Mendel and His Work on Inheritance → Gregor Johann Mendel (1822 & 1884) started his experiments on plant breeding and hybridization. He proposed the laws of inheritance in living organisms. → Mendel was known as Father of Genetics. → Plant selected by Mendel: Pisum sativum (garden pea). He used a number of contrasting characters for garden pea. When two parents cross (or breed) to produce progeny (or offspring’s), then their progeny is called first filial generation or F 1 generation (where F stands for Filial which denotes progeny of a cross). When the first generation progeny cross (or breed) among themselves to produce second generation progeny, then this progeny is called second filial generation or F 2 generation Seven pairs of contrasting characters in Garden Pea Medal’s Experimental Material He chose Garden Pea (Pisum sativum) as his experiment material because of: → Availability of detectable contrasting traits of several characters. → Short life span of the plant. → Normally allows self-fertilization but cross-fertilization can also be carried out. → Large no. of seeds produced. Mendel’s Experiments: Mendel conducted a series of experiments in which he crossed the pollinated plants to study one character (at a time).  The Principle of Dominance or Law of Dominance: When two homozygous individuals with one or more sets of contrasting characters are crossed the characters that appear in the F1 hybrids are dominant characters and those which do not appear in F1 are recessive characters.   The Principle of Segregation or Law of Segregation: (Law of purity of gametes) The law of segregation states that when a pair of contrasting factors or genes or alleles are brought together in a heterozygous condition, the two remains together without being contaminated but when gametes are formed from them the two separate out from each other. This is also known as Mendel's first law of heredity.  The Principle of Independent Assortment or Law of Independent Assortment: If the inheritance of more than one pair of characters is studied simultaneously, the factors or genes for each pair of characters as sort out independently. It is called as Mendel's second law of heredity. RECALL QUESTION 1. Explain Mendel’s concept of heredity, by giving three points. 2. Why Mendel choose pea plant for is experiment 3. What are the contrasting character in pea plant? 4. What is a dominant trait with respect to height in pea plant. Give any two examples Monohybrid Cross: Cross between two pea plants with one pair of contrasting characters is called a monohybrid cross. Mendel took two types of pea plants – a tall plant and a short plant, produced progeny from them, and calculated the percentages of tall or short progeny. he took pure tall (genotype TT) and pure dwarf (genotype tt) pea plants and cross pollinated them to obtain first generation or first filial generation. In this figuration (F1 generation) he obtained only tall plants. This meant that only one of the parental traits was seen, not the mixture of the two. The plants of F generation or progeny are then self-pollinated to obtain F2 generation or progeny. Now all plants were not tall. Observations from experiment were: → In first generation (F1), all plants were tall. → In second generation (F2), one quarter of plants were short and others were tall. → Both the tallness and dwarfness traits were inherited in the F1 plants, but only the tallness trait was expressed. Tallness is a dominant trait and dwarfness is a recessive trait. → Thus, two copies of the trait are inherited in each sexually reproducing organism Conclusions → TT and Tt both are tall plants while tt is a short plant. →A single copy of T is enough to make the plant tall, while both copies have to be ‘t’ for the plant to be short. → Characters/traits like ‘T’ are called dominant trait (because it express itself) and ‘t’ are recessive trait (because it remains suppressed). Recall question (practice definition of monohybrid cross with the law) 1.. How do Mendel’s experiments show that the traits may be dominant or recessive (need to practice in all the possible traits)? 2. An angiosperm plant having red colored flowers when crossed with the other having the same color produced 40 progenies, out of which 30 plants were with red colored flowers, 10 plants were with white colored flowers. Find out: a. What is the possible genotype of parent plants? b. Which trait is dominant and recessive? c. What is this cross called as and what is its phenotypic ratio 3.. A pea plant with blue color flower denoted by BB is cross-breed with a pea plant with white flower denoted by ww. a. What is the expected color of the flowers in their F1 progeny? b. What will be the percentage of plants bearing white flower in F2 generation, when the flowers of F1 plants were selfed c. State the expected ratio of the genotypes BB and Bw in the F2 progeny 4. A violet pea plant [VV] was crossed with a white one[vv]. F1 generation was allowed to self pollinate and F2 generation was also obtained, Answer the following questions: a. What would be the phenotype of plants in F1 generation? b. What would be the percentage of plants with white flowers in F2 generation? c. What would be the ratio of vv: Vv in F2 generation 5. a. What are monohybrid and dihybrid cross? b. How Mendel proved that tallness is the dominant trait and dwarfness is recessive in a pea plant? Explain with the help of a monohybrid cross Dihybrid Cross: Cross between two pea plants with two pairs of contrasting characters each at the same time is called a dihybrid cross. Or Mendel also carried out experiments to observe inheritance of two pairs of contrasting characters from two plants at the same time, which is called dihybrid cross. He crosses breed pea plants bearing round green seed with plants bearing wrinkled and yellow seeds. In the F1 generation he obtained all round and yellow seeds it means round and yellow traits of seeds are dominant features while wrinkled and green are recessive. He self-pollinated the plants of F: generation to obtain F2 generation, Mendel crossed between pea plants bearing round green seeds and pea plants bearing wrinkled and yellow seeds. Phenotypic Ratio Round, yellow : 9 Round, green : 3 Wrinkled, yellow : 3 Wrinkled, green : 1 Observations from experiment were: → In F1 generation, all plants had round and yellow seeds. Thus, round and yellow are dominant traits and wrinkled and green are recessive traits. → In F2 generation, four different types of seeds were obtained. They were - round yellow, round green, wrinkled yellow and wrinkled green in the ratio of 9 : 3 : 3 : 1. → Occurrence of new phenotype combinations shows that traits are independently inherited. Conclusions → Round and yellow seeds are Dominant characters. → Occurrence of new phenotype combinations show that genes for round and yellow seeds are inherited independently of each other. Recall question 1.How do Mendel’s experiment show that traits are inherited independently (practice dihybrid cross with different trade with the law and ratio of genotype and phenotype) 2 Mendel done cross between Round yellow seed with wrinkle green seed. As a result, he got 2160 seed. Find out the number of round green seed and wrinkle yellow seed. (practice calculation in dihybrid and monohybrid cross) How do these traits get expressed → Cellular DNA is the information source for making proteins in the cell. → A section of DNA that provides information for one protein is called the gene for that protein. → Plant height can thus depend on the amount of a particular plant hormone. The amount of the plant hormone made will depend on the efficiency of the process for making it. Cellular DNA (Information source) → For synthesis of Proteins (Enzyme) → Works efficiently → More Hormone → produced Tallness of plant Therefore, genes control characteristics/traits. SEX DETERMINATION – 1.The mechanism of determining the sex of an individual is known as sex determination. 2.In some organisms, environmental factors such as temperature determine the sex of the organism in the egg. 3.Each human cell contains 23 pairs (46 numbers) of chromosomes, out of which 22 pairs are called autosomes, which are similar in both males and females and are responsible for the various characteristics of an individual. The last pair is that of the sex chromosomes that determine the sex of the individual. Sex chromosomes in humans are of two types X and Y. 4.Females have two X chromosomes in their cells while males have one X and one Y in their cells. 5.When the sperm containing the X chromosome fertilizes the egg, then the zygote develops into a female. When the sperm containing the Y chromosome fertilizes the egg, then the zygote develops into a male. All children will inherit an X chromosome from their mother, despite whether they are a boy or girl. Thus, the sex of the children will be determined by the type of chromosome inherited from their father. A child who inherits Y chromosome will be a boy and who inherits X chromosome will be a girl. FACTORS RESPONSIBLE FOR SEX DETERMINATION: 1. Genetic Combination Sex determination in humans: (A mechanism by which sex of new born baby is determined). Autosomes: These determine the somatic traits. There are 22 pairs of autosomes in humans. Sex chromosome: Chromosome which determine the sex of a person. (X & Y). There is one pair of sex chromosome in humans which may be XX or XY In male – One X chromosome and one Y chromosome In female- Two X chromosome (no Y chromosome) Environmental factor – temperature – eg :- crocodiles ( reptiles)(Snails :- individuals can change Sex Recall question 1. How many pairs of chromosomes are present in human beings? Out of these how many are sex chromosomes? How many types of sex chromosomes are found in human beings? 2. Woman are often blamed for bearing daughters. As a student with knowledge in science how will you explain it to your fellow students that the sex of the child is not determined by mother’s genetic contribution 3. Explain the manner in which sex is determined in human beings 4. Explain how equal genetic contribution of male and female parents is ensured in progeny 5. a. What is the genetic constitution of human sperm? b. Mention the chromosomes pair present in zygote determining the sex of a male child 6.explain how environmental will determine the sex of the organisms, give some example. The possible genotypes of a man with blood type B are BB or BO and the genotype of a woman with blood type AB is AB. The child would receive an A allele or a B allele from the mother and a B allele or an O allele from the father. Therefore, the child could not possibly be of blood type O. The following diagrams are Punnett squares for the two possible combinations, i.e. AB x BB or AB x BO OUR ENVIRONMENT Ecosystem → All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem. E.g., forest, pond etc. Types of ecosystem It is of two types (i) Natural ecosystem: The ecosystem which exists in nature on its own. Example: forest, lake, ocean. (ii) Artificial ecosystem: Man-made ecosystems are called artificial ecosystems. Example: crop field, aquarium, garden. (i) Abiotic Components: All the nonliving components such as air, water, land, light, temperature etc. form the abiotic components. (ii) Biotic Components: All the living components such as plants, animals, bacteria, fungi etc. form the biotic components. Q1: "Although gardens are created by man, they are considered to be an ecosystem." Justify this statement. (2023) Q2: (A) Why is a kitchen garden called an artificial ecosystem while a forest is considered to be a natural ecosystem? (B) While designing an artificial ecosystem at home, write any two things to be kept in mind to convert it into a self-sustaining system. Give reason to justify your answer. (CBSE 2023) Q3: (i) Why are crop fields considered as artificial ecosystems? Q4: (i) List two human-made ecosystems. (ii) "We do not clean a pond in the same manner as we do in an aquarium." Give reason to justify this statement. (Term II, 2021-22) Q5: (a) We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Why? Q6: What are consumers? Name the four categories under which the consumers are further classified. (2021 C) Decomposer and its importance in eco system: Include organisms which decompose the dead plants and animals. Example: bacteria, fungi. These help in the replenishment of natural resources. Q6: State one ill-effect of the absence of decomposers from a natural ecosystem. → Food chain is a series of organisms in which one organism eats another organism as food. For example: Grass → Deer → Lion → In a food chain various steps where transfer of energy takes place is called a trophic level. Q7: Write a common food chain of four steps operating in a terrestrial ecosystem. (2022 C) Flow of energy between trophic levels → Flow of energy in a food chain is unidirectional. → Green plants capture 1% of sunlight and convert it into food energy. → 10 percent law : Only 10% of energy is transferred to the next trophic level. The remaining 90% energy is used in life processes (digestion, growth, reproduction etc.) by present trophic level. → Due to this gradual decrease in energy, food chains contain 3-4 trophic levels.  Trophic levels Decrease in energy 1 kJ ↣ 10 kJ ↣ 100 kJ ↣ 1000 kJ Q8: 20,000 J of energy was transferred by the producers to the organism of second trophic level. Calculate the amount of energy that will be transferred by organisms of the third trophic level to the organisms of the fourth trophic level. Q9: In the following food chain, only 2J of energy was available to the peacocks. How much energy would have been present in Grass? Justify your answer. Grass → Grasshopper → Frog → Snake Peacock (Term II, 2021-22) Q10: Name the group of organisms which form in the first trophic level of all food chains. Why are they called so? Biological magnification: The concentration of harmful chemicals increases with every next trophic level in a food chain. This is called biological magnification. → Maximum concentration of such chemicals accumulates in human bodies as humans occupy the top level in any food chain. Q11: Use of several pesticides which results in excessive accumulation of pesticides in rivers or ponds, is a matter of deep concern. Justify this statement. (2023) Q12: How do harmful chemicals get accumulated progressively at each trophic level in a food chain? (CBSE 2023) Q13: Why are human beings most adversely affected by bio magnification? Q14: What is the difference between food chain and food web? → In nature large numbers of food chains are interconnected forming a food web. Environmental problems: Changes in the environment affect us and our activities change the environment around us. Human activities lead to pollution, deforestation etc.  Ozone layer → Ozone layer is a protective blanket around the earth which absorbs most of the harmful UV (ultraviolet) radiations of the sunlight, thus protecting living beings from many health hazards such as skin cancer, cataract, destruction of plants etc. → Ozone (O3) layer is present at higher levels of the atmosphere (i.e. stratosphere). It is a deadly poison at ground level. Formation of ozone molecule (i) The high energy UV radiations break down the O2 molecules into free oxygen (O) atoms. O →(UV) O + O (atoms) (ii) These oxygen atoms then combine with oxygen (O2) molecules to form the ozone molecule. O2 + O → O3 (ozone) Depletion of ozone layer → The decrease in the thickness of the ozone layer over Antarctica was first observed in 1985 and was termed an ozone hole. → This decrease was linked to excessive use of synthetic chemicals like chlorofluorocarbons (CFCs) which are used in refrigerators, ACs, fire-extinguishers, aerosols, sprays etc. → United Nations Environment Programme (UNEP) succeeded in forging an agreement to stop CFC production at 1986 levels (KYOTO PROTOCOL) by all countries. Q15: How is ozone formed in the higher levels of the atmosphere? "Damage to the ozone layer is a cause of concern." Justify this statement. (2023) Q16: What is ozone? How is it formed in the upper layers of the earth's atmosphere? How does ozone affect our ecosystem? (2022) Q17: Why is the ozone layer getting depleted at the higher levels of the atmosphere? Q18: Mention one harmful effect caused by its depletion. (2022) Garbage disposal → Improvements in lifestyle have resulted in accumulation of large amounts of waste materials. Types of materials in Garbage (i) Biodegradable: Substances which can be decomposed by the action of microorganisms are called biodegradable wastes. Example: fruit and vegetable peels, cotton, jute, dung, paper, etc. (ii) Non-biodegradable wastes: Substances which cannot be decomposed by the action of microorganisms are called non-biodegradable wastes. Example: plastic, polythenes, metals, synthetic fibres, radioactive wastes, pesticides etc. → Micro-organisms release enzymes which decompose the materials but these enzymes are specific in their action that’s why enzymes cannot decompose all the materials. Q19: What is the difference between biodegradable and non-biodegradable substances? List two methods of safe disposal of biodegradable domestic waste. (2023) Methods of waste disposal (i) Biogas plant: Biodegradable waste can be used in biogas plants to produce biogas and manure. (ii) Sewage treatment plant: The drain water can be cleaned in sewage treatment plants before adding it to rivers. (iii) Land fillings: The wastes are buried in low lying areas and are compacted by rolling with bulldozers. (iv) Composting: Organic wastes are filled in a compost pit and covered with a layer of soil, after about three months’ garbage changes to manure. (v) Recycling: Non-biodegradable wastes are recycled to make new items. (vi) Reuse: It is a conventional technique to use an item again. Example: newspaper for making envelopes. Q20: Kulhads (disposable cups made of day) and disposable paper cups both are used as an alternative for disposable plastic cups. Which one of these two can be considered as a better alternative to plastic cups and why? (2022) Q21: What is meant by garbage? List two classes into which garbage is classified. Q22: What do we actually mean when we say that "enzymes are specific in their action”? (2022) Note: 1. Practice all Activity Based questions in all the Chapters