1.Male produces two types of sperm (X & Y type in the ratio 1,: 1), Female produces only one type of ovum (X type), hence the sex of baby is determined by the type of sperm fertilizing the ovum. Therefore women should not be blamed 
2. A genetic doss showing sex determination in human beings covering above value points can be considered in lieu of the explanation.
3.Sensitivity" towards community" / Social awareness / Self discipline /Responsible behaviour / Leadership quality! Caring attitude I Responsible attitude towards society / Concern for others / Sharing of kf\pwledge or information I Presence of mind / Being'proactive I any other relevant value.

(a)Reduce air pollution, improve exposure/sensitivity of the children to the environment to reduce vulnerability, improve resistance,improve food habits, resulting in good health, introduce physical exercise (any other appropriate measure).
(b)Mites in dust pollen, animal dander. (any two) Immune system respond by producing antibodies of lgE type, inducing Mast cells release cl}emic<vs like histamine/serotonin ln response to allergens.

(b) Sickle-cell anaemia and Haemophilia.
(c) Sickle-cell anaemia
The RBCs become elongated and sickle-shaped, as the mutant haemoglobin undergoes polymerisation under low oxygen  tension.
Haemophilia
One of the proteins involved in the clotting of blood is affected; blood clotting is much delayed and there is non-stop bleeding from even a small cut.

(a) The genes for haemophilia and colour blindness are present on the X-chromosome.
a.A male has only one X-chromosome and bears only one allele for the trait i.e. he is hemizygous for the trait, as V-chromosome does not have a corresponding allele.
b. A female has two X-chromosomes, received one from each of her parents; she has to be homozygous recessive, i.e. her father must be a sufferer and mother either a sufferer or a carrier, to develop the disease.
(b) The zygote will be XXV and develop into a male with Klinefelter's syndrome.
1. Such individuals are sterile.
2. They show gynaecomastia and feminine characters.
3.To avoid such a hereditary disorder, the woman was advised MTP.

(i) Seed shape shows complete dominance. Heterozygotes produce the round seeds.
(ii) Size of starch grains shows incomplete dominance. Heterozygotesproduce intermediate sized starch grains in seeds.

Size of starch grain is an example of incomplete dominance, whereas in Mendelian inheritance, seed shape shows complete dominance.

Thalassemia is categorised as a Mendelian disorder, because it. is an autosomal, recessively-inherited disorder, whose transmission follows Mendel's laws/ principles of inheritance.
(i) The disease is caused by mutation or deletion of the alleles and there is reduced synthesis of alpha or beta globin chain of hemoglobin.
(ii) The symptom is anemia, which is due to less synthesis of hemoglobin.

(a)A female (mother) is homogametic and produces ova, all containing one X-chromosome and 22 autosomes.
A male (father) is heterogametic and produces sperms of two types-50% of them carrying one X-chromosome and the other 50% carrying V-chromosome and 22 autosomes each.
The sex of the child is determined by, the type of sperm fertilising the ovum.
If the ovum is fertilized by a sperm carrying X-chromosome, female child results
If the ovum is fertilised by a sperm carrying V-chromosome, a male child is formed.


(b)

(b) (i) The egg cell on fertilisation becomes the zygote, which later forms the embryo
(ii) The polar nuclei fuse to form a diploid secondary nucleus; on fertilisation by a male gamete, it forms the primary endosperm nucleus, which later forms the endosperm.

(i) Insect-pollinated flowers are large, colourful and showy; if flowers are small, they are clustered into inflorescene to make them conspicuous.
(ii) The pollen grains and stigmatic surface are sticky.
(iii) They are highly fragrant; flowers pollinated by flies and beetle have foul odours to attract them.
(iv) To sustain animal visits, the flowers offer certain rewards like nectar, edible pollen and safe place for laying eggs.

(a) Syngamy
Syngamy refers to the fusion of a male gamete with the female gamete in the embryo sac to form a diploid zygote.
Triple fusion
Triple fusion refers to the fusion of a male gamete with the secondary nucleus (formed by fusion of two haploid polar nuclei) to form the triploid primary endosperm nucleus.
(b) Embryo development
Th'e zygote undergoes mitotic divisions during embryogeny.
The first division is transverse and results in a basal cell and a terminal cell; the basal cell forms the suspensor while the terminal cell forms the embryo proper.
It first, forms a filamentous proembryo, which later forms in sequence a globular embryo, heart-shaped embryo and then a mature embryo.

(a) Development of Pollen grain:
   - Microsporocytes undergo mitotic divisions to increase the number of functional microspore mother cells.
   - Each microspore mother cell undergoes meiosis to form a microspore tetrad.
   - All the four microspores remain enclosed in a common wall.
   - They start separating from each other.
   - The nucleus undergoes a mitotic division resulting in the formation of a large vegetative cell and a small generative cell.
   - The spore develops a wall of two layers the outer- exine and inner intine.
   - At this stage, the pollen grains are liberated; but in some cereals the generative cell undergoes mitosis and the pollen grain is 3-celled, at the time of liberation.
(b) Mature Pollen Grain:
   - A mature pollen grain has a protective covering of two layers.
   - The outer is thick, sculptured variously and is made of sporopollenin; this layer is called exine.
   - The inner layer, called intine is thin and is made of cellulose.
   - A mature pollen grain is two celled with a large vegetative cell and a small generative cell floating in the cytoplasm of the vegetative cell.
   - The pollen grains of dicot plants have three germ pores while those of monocots have one.