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Evolution and clinate change
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Palaeontology
Palaeontology
Evolution of Raga and Tala
Assignment Topic: Effects of heredity and environment on development of personality. Answer: Introduction: Personality is a set of qualities or attributes that make a person (or thing) distinct fr...
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Human Evolution
The nature to nurture debate. How heredity or environment impacts on human behavior.Full description
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Descripción: Human Evolution
history
Program LECTURE NOTES – BIOLOGY STEPS … A __________________________ _________________________________________ _____________________________ __________________________ ___________________________ ____________________ _____
– Heredity – Variation – genetics – Mendel’s factor – Chromosome – genes – DNA – Structure of Chromosome – Karyotype – DNA – Sex Determination – Organic evolution–evidences – Theories of Evolution •
In asexual reproduction, all the off springs are exactly identical to one another as well as to parents because of same same genetic makeup. makeup.
•
In sexual reproduction the various off springs are similar to their parents but are not identical to items or to one another because of genetic various except IDENTICAL TWINS.
•
Identical Twins: grow from a single cell which splits after fertilization. Look alike
•
Non Identical twins: Look less like they grow from 2 different fertilized cells & hence don’t have exactly same genetic material.
•
Heredity: The transmission of characters characters (traits) from from the parents to to their off springs is called Heredity.
•
Variation: The differences in the characters among the individuals of a species is called variation is necessity for organic evolution.
Both Heredity & variation are fundamental factors in the process of Evolution of an organism. •
Genetics: The branch of biology which studies heredity & variation is called genetic.
•
Terms gene was coined by scientist – Johanssen in 1909.
•
Chromosomes: Chromosomes are thread like structures present in the nucleus of a cell which contain hereditary information of the cell. They are made up of DNA & proteins.
chromatids
centromere
Chromosome 2 chromatids
=
1 chromosome
One species
=
fixed no. of chromosome
Humans
=
46 chromosomes = 23 pairs of homologues chromosomes
STEPS _________________________ ______________________________________ ________________________ ______________________ ___________ th Get free chapterwise tests for Class X on www.tcyonline.com
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Program LECTURE NOTES – BIOLOGY STEPS … A __________________________ ________________________________________ ___________________________ ___________________________ ____________________________ ____________________ ______ (Same size and Shape)
Types:
Metacentric •
Sub–Metacentric
Acrocentric
Telocentric
Dipoid Cell: A cell which has the full no. of chromosomes with two of each pair, is called a diploid us.
•
Hiploid Cell: A cell
c
half the no. of chromosomes with one of each pair e.g. gamete
cell/sex cell. •
Autosomes: All the chromosomes in a cell (except sex chromosomes) are called autosomes.
•
Karyotype: During metaphase stage of cell division, the chromosomes become shorter, thicker & can be seen very clearly. In order to study the no. shape, size and type of chromosomes of an individual, the chromosomes during melaphase, are arranged acc to their length & position of centromere. centromere. Such an arrangement of of chromosomes chromosomes for the purpose of studying is called Karyotype. Identifying a chromosome thru microscope, special staming technique called “Banding Technique” is used. Study of karyotype of an individual helps in the diagnosis of genetically disorders.
Down’s Syndrome: Any variation in the no. of chromosomes from the normal no or any change in the shape of chromosome during fertilization can lead to severe abnormality or disorder in the child after birth which are called Genetic / Heredity Disorder e.g. Down’s syndrome which is caused by interitance of an extra 21 st chromosome. In this syndrome, full mental development does not take place. Symptoms: Mental retardation, Flattened , nose, Defective ears, widely separated eyes, short & broad neck, protruding tongue, tongue, small & sturdy hands widely. Gene: Gene is the unit of inheritance. Various genes are located in the chromosomes at fixed position genes are responsible for our characteristic features. Chemically gene is a segment of a large polynucleotide molecule called deoxyribonucleic acid DNA: Dexyribo nucleic acid DNA was first isolated by Frederick meisher from the nucleus of the pus cells. It is acidic in nature so the name is nucleic acid.
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STEPS __________________________ _______________________________________ ________________________ _____________________ __________ th Get free chapterwise tests for Class X on www.tcyonline.com
Program LECTURE NOTES – BIOLOGY STEPS … A __________________________ _________________________________________ _____________________________ __________________________ ___________________________ ____________________ _____ DNA is a macromolecule/polymer which is made up of a large no. of smaller units called
Nucleotide. So DNA is a polynucleotide. Nucleotide Nucleotide is the basic structure unit of DNA. Components Components of a Nu cleotide: cleotide: 1.
a nitrogen containg base
2.
a pentose sugar
3.
a phosphate gp
A Purines G C Purimidiness T
Any one of nitrogen base pairs up only
c
a specific nitrogenous base of the opposite side. Such
specific pairing is called COMPLIMENTARY PAIRING. (Adenine) A pairs up
c
T
(Cytosome) C pairs up
c
(Thymine) G
(Guanine)
DNA molecule is like that of a spiral staircase in which both the railing of the staircase are made of sugar & phosphate molecules alternative each other and held together by strong chemical bonds whereas the steps of the staircase are made of complimentary nitrogenous bases held together by weak bonds. N.B.: DNA structure established by Wastson & Crick in 1953. Each helical turn of the DNA molecule has a length of 3.4 nm in which 10 nucleotide units are present.
Pentose sugar Phosphate gp A – Adenine T – Thymine C – Cytosine G – Guanine A B •
T G
Complimentary Complimentary parsing
Genetic Engineering: The technique for altering an organisms genetic make up inserting genes from other organism its chromosomes is called Genetic Engineering.
•
Sex Determination: The process by which the sex of a per is determined is called sex determination.
STEPS _________________________ ______________________________________ ________________________ ______________________ ___________ th Get free chapterwise tests for Class X on www.tcyonline.com
3
Program LECTURE NOTES – BIOLOGY STEPS … A __________________________ ________________________________________ ___________________________ ___________________________ ____________________________ ____________________ ______ The Chromosomes Chromosomes which determine the sex of a person called sex chromosomes which are
of 2 types X & Y.
Q
Males X&Y
Female
XX Child) (Female Child)
XY
X X
Zygote
(Male
XX combination is always found in females XY combination is always found in males. So it is the sperm (carrying either X or Y) which determines the sex of a child ORGANIC EVOLUTION
Evolution is the sequence of gradual changes which take place in the primitive organisms over millions of yrs. In which non species are provided. Some imp. Sources which provide evidence for organic evolution are •
Fossils
•
Homologus Homologus organs
•
Analogus organs
•
Vestigial organ
•
Embryology
•
Homologus organ: Organs having similar basic structure & origin but different functions e.g. porelnubs
•
Analogous
of a frog, birds & man.
organs: The organs with different basic structure but have similar
appearance & performs similar functions. e.g. wings of an insect & a bird. •
Vestigial organs: Organs which are functionless useless but were functional in aucestors e.g. Vermiform appendix Nietuting membrame.
•
Embrgology: The study of the development of the embryo of an animal is called Embrgoloy.
•
Biogenetic law : It states chat “Ontogeny recapitulates recapitulates Phylogeny” It means that during the development of the embryo of any organism, its complete evolutionary history is repeated. THEORIES OF EVOLUTION
1.
Lamarckism
1.
Lamarckism: It states (a)
2.
Darwinism
3.
Synthetic Theory of Evolution
The use & disuse of of an organ organ by an organism leads to acquiring of of variation in the features of that organ.
4
(b)
These variations (acquired characters) are inherited by the the offsprings.
(c)
This leads to evolution
STEPS __________________________ _______________________________________ ________________________ _____________________ __________ th Get free chapterwise tests for Class X on www.tcyonline.com
Program LECTURE NOTES – BIOLOGY STEPS … A __________________________ _________________________________________ _____________________________ __________________________ ___________________________ ____________________ _____ This theory was criticsed by August weismann who ejected the idea of inheritance of acquired
characteristics. DARWI NISM / Theory of Natural Selection Selection (a)
All the species species produce produce a large no of offsprings offsprings but population remains fairly constant due due to struggle bt the members of same species & different species for food, space & mate
(b)
This struggle struggle eliminates the unfit individuals. (Survival of the fittest)
(c)
This gives orgin to variations which pass into progeny & over a long period of time, time, leads to origin of new species.
Limitations: It could not explain how the variations arise. Synthetic Theory of Evolution: The most accepted theory these a days which says that “origin of species is based on the interaction of genetic variation & natural selection’.
STEPS _________________________ ______________________________________ ________________________ ______________________ ___________ th Get free chapterwise tests for Class X on www.tcyonline.com