(a) Down's Syndrome 

(d) All of the above

The first menstruation begins at puberty and is called menarche.

Agrobacterium tumefaciens.

(b) T-Lymphocytes

Sciophytes are the shade loving trees or plants. These plants have larger photosynthetic units than sun plants. They reach their saturation level in only 20% sunlight

(b)Bulb.

The multiple effect of a gene is called pleiotropy

• Ori stands for origin of replications.
• It is a sequence from where replication starts.
• It is a specific position of plasmid genome that serves as a start signal for self-replication.
• It is desirable that cloning of target DNA should be carried out in such a vector where origin facilitates a high copy number.

The pyramid of energy is always upright. Pyramid of energy is a graphical representation amount of accumulated energy per unit area at different trophic levels in a food chain.

Emasculation:Removal of stamens or anthers or killing the pollen grains of a flower without affecting the female reproductive organs is called emasculation.

Uses:

• It is essential in bisexual flowers to prevent self-pollination.
• By practicing emasculation, the plant breeder makes a female flower which can be artificially pollinated by the desired pollen grains.

The expression of the traits of two pure parents as an intermediate condition or fine mixture in the F1 hybrids is known as incomplete or partial dominance. It is also called blended or intermediate or mosaic inheritance.

FOR EXAMPLE:-

Parents.

Phenotype:   pure red flower      *      pure white flower

Genotype:      RR                                        WW

Gametes:       R R                                         W W

F1 gen:-

R                 R                                                   

W                                                           

W

Genotypic ratio:   RW : RW : RW : RW

1   :   1   :  1    :  1  

Phenotype =>All hybrids pink.

F2 gen:- (self-cross)                   

R                  W

R

W

Genotypic ratio:-  RR : RW : RW : WW.

1  :      2          :  1 

Phenotype:- pure red  : hybrid pink : pure white.

Bio piracy is the robbery or stealing of biological and genetic resources which are indigenous to a particular country.

Its main impacts are:-

• Bio piracy by western corporations robs intellectual contributions of another country and wealth, hence creating intellectual poverty.
• Bio pirates steal certain useful biological material for their enrichment.

Rhizobium bacteria show symbiotic association with the roots of leguminous plants.

• This bacteria fails to fix atmospheric nitrogen in its free state. It is present inside soil in free state. It multiplies when multiplies when it enters the roots of surrounding areas ie rhizosphere.
• When the plant dies, the fixed nitrogen is released, making it available to other plants. This helps to fertilize the soil.

The effects of alcohol on the liver :-

• In the liver alcohol is converted into a more toxic substance, acetaldehyde.
• Liver synthesizes fats from alcohol. The excess fats reduce formation of glycogen enzymes and structural proteins.
• Thus the liver changes from being an important centre of carbohydrate, fat and protein metabolism to a mere store house of fat. This causes fatty liver syndrome.

Phenotypic adaptation:- Non genetic change in an individual is called phenotypic adaptation. Phenotypic adaptation involves changes in the body of an organism in response to a genetic mutation or certain environmental changes. These responsive adjustments occur in order to cope with environmental conditions present in their natural habitats.

For example:-

• Morphological and physiological adaptations.

Animals with constant body temperature called homeotherms have an insulation layer to prevent loss of body heat. This layer consists of hair in most mammals, blubber in whales and seals and feathers in birds.

Shivering warms up the body and perspiration or panting cools down the body of these animals when required. These are also called endotherms.

• Behavioural adaptations:-

The animals with variable temperature called poikilotherms are affected by temperature variations more than homeotherms.

They are also called ectotherms (cold-blooded animals). Their body temperature varies with environmental temperature in which they live. They fight temperature variation in the following manner.

1. Hibernation:-  insects, molluscs, amphibians, reptiles and even some mammals escape cold by hiding in frost free shelters such caves, burrows, crevices, hollow tree trunks and mud. It is also known as winter sleep.
2. Aestivation:- several insects, certain spiders, molluscs, fish, reptiles and mammals living in hot and dry regions undergo aestivation. It is also known as summer sleep.
3. Winter eggs:- in some animals, adults die as winter approaches race is maintained by means of “winter eggs” which can withstand the coldweather.

1. Particle bombardment gun method:-

This method was first developed by prof. Stanford and co-workers at Cornell University, USA in 1987. The technique involves shooting foreign DNA into plant cells at a very high velocity. This method is also known as biolistic  technique.

In this method, a 1-2μm gold or tungsten particles coated with DNA are shot into plant cells using a helium pressure particle gun device.

Important crops and plants like wheat, rice and maize have now been transformed by this method.

2. Micro injection:- in this method, the DNA solution is injected directly inside the cell using capillary glass micropipettes or a micro syringe. This technique was originally used in animal cells but is now applied to plant cells also. However, the method of injection requires great technical skill because many cells die during the process.

Human genome project is a comprehensive international effort that started in the year 1990 by molecular biologists to develop ways of mapping human genome to a finer level.

• It was developed to store this information on a database and tools for development and for data analysis.
• To note the ethical, social and legal issues of this project.
• HGP consists of approximately three billion base pairs(3*10bp), and if the cost of sequencing a single base pair required about US $3, then the overall expenditure was estimated to be approximately 9 billion US dollars to complete this project.
• If the data is to be stored in books with each book having 1000 pages and each page having 1000 letters, 3300 books would be required. Therefore, this project is also known as human mega project.

SALIENT FEATURES OF HUMAN GENOME:-

• The total number of nucleotide bases present in the human genome is 3164.7 million.
• The average gene has 3000 bases, but their sizes vary greatly. The largest human gene is dystrophin, which contains 2.4 million bases.
• The total number of genes contained in a human genome is about 30,000. Earlier this number was thought to be 80,000 to 1,40,000 genes.
• The maximum number of genes 2968 are found in chromosome I whereas minimum number 231 are found in Y-chromosome of human genome.
• Almost all nucleotide bases are exactly the same in all human beings.
• Functions of more than 50% of the discovered genes are not known.

Test tube baby programme:-  This method involves in vitro fertilisation (IVF) ie fertilisation of male gamete (spermatozoa) and female gamete (ovum) outside the body in almost similar conditions as that in the body followed by zygote or embryo transfer (ET).

1. Test tube baby:-in some women, normal conception is not possible because of blocked oviducts or spermicidal secretions in the vagina or low sperm count of the husband. There are also cases where women can’t produce ova or men can’t produce sperms.

In all such cases, ovum from the wife/donor female is removed surgically after hormonal stimulation of the follicles.

It is then fertilized by her husband’s/male donor’s sperm in a laboratory dish containing a nutrient bath.

2. ZIFT:- Hear the zygote or early embryo(up to 8 blastomeres stage) is transformed or transferred to the fallopian tube in a process called zygote intra fallopian transfer or embryo with more than 8 blastomeres is transferred to the uterus in a process called inter uterine transfer or IUT to complete further development of zygote or embryo.

With proper medical care, the mother will give birth to a normal child upon completion of gestation period.

Success rate of test tube babies:-

The success rate of the technique of producing test tube babies is less than 20%. To increase chances of success, the prospective mother is given fertility drugs which cause many ovarian follicles to mature at the same time. This releases many eggs simultaneously thereby increasing chances of success.

1. Biofortification:-  is a plant breeding program designed to increase vitamins, minerals, higher protein and healthier fat content in crop production.

Many crop varieties such as

• vitamin A enriched carrots, spinach, pumpkin;
• Vitamin C enriched tomato;
• Iron and Calcium enriched spinach and bathua have been released by the Indian Agricultural Research institute, New Delhi.

2. Role of microbes in household food processing

1. Curd – lactobacillus bulgaricus.
2. Dough – streptococcus faecalis.
3. Cheese (Types).

Cottage cheese.

– Streptococcus lactis.

- Propionibacterium shermanii.

Roquefort cheese.

- Penicillium roqueforti.

4. Baker’s yeast – Saccharomyces cerevisiae.
5. Sausage – Lactic acid bacteria.

Causing agent:- Entamoeba histolytica.

• Symptoms:- Severe griping pain in the abdomen.
• Fever
• Nausea and exhaustion
• Nervousness

Mode of transmission:-

Infection is caused by injecting cysts which may occur in food and drinks prepared in unhygienic conditions.

Cancer is the uncontrolled division and growth of cells.

Causes:-

• Exposure to radiation like X-rays, gamma rays etc.
• Chemical agents like caffeine, heavy metallic ions etc.
• Cigarette and cigar tobacco smoking causes lip, mouth and lung cancer.
• Jagged teeth may cause tongue cancer.