CBSE Class 12 exams 2019: The Central Board of Secondary Education (CBSE) will conduct board examinations from February for the coming academic year 2019. The board has already released a list of vocational subjects for the examinations that will be conducted from February to March 2019, the schedule and date of the examinations will be released later.
Apart from the 40 different vocational subjects, the board will conduct exams for typography and Computer Applications (English), web applications, graphics, office communication, et al, in February as these subjects have larger practical component, and shorter theory papers.
CBSE Class 12 exams 2019: Check the complete syllabus on Biology
Sexual Reproduction Pollination and fertilisation in flowering plants.
Development of seeds and fruits.
Human reproduction: Reproductive system in male and female, menstrual cycle.
Production of gametes, fertilisation, implantation, embryo development, pregnancy and parturation.
Reproductive health – birth control, contraception and sexually transmitted diseases. (Periods 35)
Key points for developing subject matter
• Plants show vegetative, asexual and sexual reproduction.
• In Angiosperms, the flowers contain the reproductive organs. They may be unisexual or bisexual.
• There are multitudes of ways of bringing together pollen and the carpel (pollination).
• In nature, pollination is subject to many uncertainties; often barriers to pollination and incompatibility have to be overcome for successful pollination and fertilisation.
• The male gametes are produced in the pollen tube, while the female gamete is produced in the embryo sac.
• Double fertilisation leads to the formation of embryo and the endosperm.
• The ovules in the ovary turn into seed after fertilisation. The ovary turns into a fruit.
• In animals, testes produce sperms and ovaries produce ova.
• Both male and female gametes production is under hormonal regulation; production of ova is a cyclic process.
• During fertilization, sperms migrate through the genital tract to fuse with the ova.
• The genetic makeup of the sperm determines the sex of the unborn child.
• The fertilised egg implants in the uterine wall where it remains connected with the mother till birth.
• The zygote undergoes cleavage, and then passes through different stages of development leading to the formation of three germinal layers.
• After completion of the gestation period, a fully developed baby is delivered.
• Contraceptive methods interfere with one or more of the following: gamete production, ovulation, sperm delivery, fusion of gametes and implantation. These methods of birth control thus help in family planning.
• In IVF the ova is fertilised using a donor sperm outsidethe body and the fertilised ova is implanted in the female body for further development.
• Abortion is legal, but not recommended for birth control; prenatal sex determination (usually associated with selective female foeticide) is illegal.
• Safe sex can help to prevent sexually transmitted diseases and AIDS.
Genetics and Evolution Mendelian inheritance
Chromosome theory of inheritance, deviations from Mendelian ratio (gene interaction- Incomplete dominance, co-dominance, complementary genes, multiple alleles).
Sex determination in human beings: XX, XY.
Linkage and crossing over.
Inheritance pattern of haemophilia and blood groups in human beings.
DNA: replication, transcription, translation
Gene expression and regulation.
Genome and Human Genome Project.
Evolution: Theories and evidences
Key points for developing subject matter
• Plants and animals show Mendelian inheritance.
• Organisms may also show cytoplasmic inheritance.
• DNA carries information from one generation to the next.
• Human inheritance pattern can be exemplified by pattern of inheritance of blood groups and haemophilia.
• Genes on the same chromosomes show linkage and are inherited together unless crossing over occurs.
• The Lac operon exemplifies a typical model of gene regulation.
• Sequencing of Human DNA under the Human Genome Project aims at finding solutions for genetic disorders and several health problems.
• DNA fingerprinting is also used for identification and crime detection.
• Diversity in animals and plants arises out of variations in the genetic material.
• Mutation is an important source of variation.
• Further, variations in genetic material would affect the entire population over generations to give rise to new species and, therefore, lead to evolution.
• The process of evolution is explained by various theories (Lamarckism, Darwinism and Neo-Darwinism). Different types of evidences support the theories.