CLASS X BIOLOGY

DAV Public School , Kailash Hills Class X Heredity and Evolution & Our environment Q1 . The genotype of green coloured Tomato plants is denoted as GG and that of purple stemmed Tomato plants as gg. When the two are crossed: a) What colour of stem would you expect in F1 progeny? b) Give the percentage of purple stemmed plants if F1 are self pollinated. c) In what ratio would you find the genotypes GG and Gg in the F2 progeny? Q2 .From the list given below, select the character which can be acquired but not inherited a) Colour of eye   b) Colour of skin  c) Size of body   d) Nature of hair Q3 .A basket of vegetables contains carrot, spinach, radish, potato, and tomato. Which one of them represent the correct homologous structures and analogous structures? Q.3 Which type of similarity , homologous and analogous occurs in the pairs of organs? a)       Forelimbs of bird and bat b)     ...

Why is there an ozone hole over Antarctica and not anywhere else? Check the link to find the answer..  

Complete your notes and NCERT Q.Ans in notebook and get it checked. Submit (individual) report on environmental topic alloted to you for integrated project.           i) Global warming     (Roll no 1-5) ii) Ozone depletion    (Roll no 6-10) iii) Rain water harvesting   (Roll no 11-15) iv) Biological magnification  (Roll No 16-20) v) The magic 3- Reduce, Recycle and Reuse   (Roll no 21-25) vi) Organic farming  (Roll no 26-30) vii) Carbon footprints- how to reduce them (Roll no 31-35) viii)Vanmahotsava (Plants that can be grown in kitchen garden/community parks.)(Roll no 36-40) ix) Disappearance of House sparrow (Roll no 41-46)        3. Revise chapter Reproduction for Science Quiz .        4. Get your practical files ( Experiments done so far) checked.

Origin of Life: Evolution can explain formation of many species ultimately from a single  species in the past. But origin of life (first species) needs further explanation. Oparin and Haldane proposed biochemical theory of evolution : Chemical evolution : Formation of simple organic substances (amino acids,  glucose, nucleotides) from inorganic substances CH4, NH3, H2S on primitive Earth. Biological/ Organic Evolution : Formation of first primitive cell using organic  molecules. Evolution of different forms of life forms from simple unicellular  prokaryotic organism Miller and Urey experiment : They simulated primitive earth. Primitive reducing atmosphere             Gases like H2S, NH3, CH4 Evaporation from hot oceans                Boiling water in flask Lightening      ...

Class XA, XB , XC : Prepare a report on the following topics: i) Global warming     (Roll no 1-5) ii) Ozone depletion    (Roll no 6-10) iii) Rain water harvesting   (Roll no 11-15) iv) Biological magnification  (Roll No 16-20) v) The magic 3- Reduce, Recycle and Reuse   (Roll no 21-25) vi) Organic farming  (Roll no 26-30) vii) Carbon footprints- how to reduce them (Roll no 31-35) viii)Vanmahotsava (Plants that can be grown in kitchen garden/community parks.)(Roll no 36-40) ix) Disappearance of House sparrow (Roll no 41-46)

Sexual Reproduction When reproduction takes place as a result of fusion of two gametes, one from each parent, it is called sexual reproduction The process of fusion of male and female gametes is called fertilization . ˜ The formation of gametes involves exchange of chromosomal (genetic) fragments between homologous chromosomes causing genetic recombination which leads to variation . Gametes : Special Reproductive cells are different from normal cells as they have half              the  number of chromosomes. e.g Human cells have 46 chromosomes but sperm and egg have 46/2=23 chromosomes. So when sperm and egg fuse, zygote will have 23+23= 46 chromosome. Male gamete : small in size and motile (has tail) Female gamete: big in size ( because of stored food reserve) and non motile. Sexual Reproduction in Plants It occurs mostly in flowering plants. In fact flowers are the reproductive organ of plants. FLOWERS ...