(4)

In fungi, hyphae are filamentous structures that branch out and spread beneath a substratum’s surface. Hyphae may rise upright above the surface during its life cycle, with its contents forming a bulge at the tip. The sporangium is formed by this bulge. Spores are generated in the sporangium.

(3)

The sporangium of the bread mould releases huge number of spores, which germinate on a suitable substratum and form hyphae. Fungi are saprophytes so profuse growth is only possible in the presence of an appropriate substratum, such as bread, that provides a considerable amount of moisture and nutrients.

(1)

The number of chromosomes in a human sperm is half the number of chromosomes in a zygote i.e., their ratio is 2 : 1.

(3)

In double fertilisation, triple fusion (vegetative fertilisation) and syngamy (generative fertilisation) occur. In generative fertilisation, a male gamete fuses with a female gamete and forms diploid zygote.

(4)

Filiform apparatus are the finger-like projections that direct the entry of pollen tube and aid in sperm discharge. The definitive nucleus is a secondary nucleus generated by the fusion of two polar nuclei. Stamens are the male parts of a flower; together, they make up the androecium.

(4)

Pollen grains are microscopic structures produced by an anther. When anther opens, pollen is released, which is subsequently transferred by the wind, insects, or birds to different plants for pollination.

(2)

Sexual reproduction is divided into 3 events: Pre-fertilisation, fertilisation and post-fertilisation events. Pre-fertilisation events occur before fusion of gametes (gametogenesis), fertilisation is the fusion of gametes to form zygote and post-fertilisation events occur after zygote formation.

(3)

Androecium consists of the anthers and filaments. They are the male reproductive structures. Male gametes that are in pollen grains are on the anthers. Depending on the species, the stamens (anthers and filaments) may or may not protrude out of the flower.

(1)

Gametes of flowers fuse to form a zygote. This zygote develops into an embryo that later forms the seed.

(1)

A – Stigma. The top part of carpel is called stigma. Stigma is for receiving the pollen grains from the anther of stamen during pollination.
B – Pollen tube. When a pollen grain falls on the stigma, it bursts open and grows a pollen tube downward through the style towards the female gamete in the ovary. A male gamete moves down the pollen tube.
C – Female gamete (ovum). It is a special reproductive female sex cell which combines with male gamete to form zygote.

(3)

In a flower, the parts that produce male and female gametes are anther and ovary respectively. Stamen is the male reproductive unit of the flower. It contains a bilobed anther at the top which produces male gametes. Filament is the stalk of the stamen that supports anther.
Pistil (carpel) is the female reproductive part of the flower. It consists of ovary (forms ovules-female gametes), stigma (receives pollen) and style (elongated tube).

(3)

The correct sequence of events are:
Pollination (transfer of pollen from stamen to stigma)
$\downarrow$
Fertilisation (fusion of germ cells to form zygote)
$\downarrow$
Embryo formation (zygote divides several times to form an embryo within the ovule)
$\downarrow$
Seedling (ovule develops a tough coat and converts into a seed)

(4)

Flowers are the sexual reproductive organs of a plant. They are produced in angiosperms. Majority of flowers are bisexual. After fertilisation, they give rise to fruits.

(2)

The flowers which are unisexual (papaya, watermelon) contain either stamens or carpels. Since only one reproductive organ is present in them, they depend on cross pollination to form zygote after fertilisation. Both stamen and carpels are required for fertilisation, so only one of them cannot produce fruits.

(3)

Sexual reproduction creates variation in organisms. So, clones cannot be produced through it. Clones are identical copies of parent organism. Sexual reproduction needs two type of gametes, i.e., male and female to form zygote after fertilisation.

(3)

Plumule ‘A’ grows into shoots, cotyledon ‘B’ stores food and radicle ‘C’ grows into roots.

(4)

Y represents the testes that produce sperms and W represents the Seminal vesicle that produces seminal fluid.

(1)

Sperm is synthesized only by the testes. The prostate gland and seminal vesicles are found outside the testes along the path of vas deferens. Secretions from the prostate gland and seminal vesicle glands contribute to the composition of semen. The seminal vesicles secretions include fructose and nourishment for sperm cells. Secretions from the prostate gland contribute to the fluid in semen.

(2)

Formation of germ cells or sperms takes place in the testes and it lies in the scrotum. In the scrotum (outside the abdominal cavity), the temperature is about 3°C lower than the temperature of the body. Testes lie in scrotum because the sperm formation requires a lower temperature than the normal body temperature.

(3)

Development of placenta and secretion of estrogen are related to female reproductive system, hence are not the function of testes at puberty.

(1)

Sperms formed in testis are delivered through the vas deferens which joins with another tube called urethra coming from the urinary bladder.

(4)

Cracking of voice is associated with sexual maturity in boys which occurs during adolescence. Loss of milk teeth, height gain, and weight gain are all part of the natural growing process for both boys and girls as they become older.

(3)

The ovaries, fallopian tubes, uterus, vagina, and external genitals make up the female reproductive system. Vas deferens is a male reproductive organ that connects the epididymis to the urethra and transports sperm from the testis to the urethra.

(4)

Female sterilisation via tubal ligation, commonly known as “tied tubes”, transcervical sterilisation, and male sterilisation or vasectomy are the three types of permanent birth control.

(3)

Infected blood, semen, and vaginal secretions contain the hepatitis B virus. It is a Sexually Transmitted Infection (STI) that spreads through unprotected sexual contact and also by contaminated needles and syringes.

(2)

Hepatitis is a virus-induced inflammation of the liver that spreads through the person’s body fluids, blood, and other bodily fluids. Syphilis and Gonorrhoea are sexually transmitted bacterial diseases. AIDS is a sexually transmitted viral disease caused by HIV.

(2)

Sexual reproduction is a process in which two individuals of the same species collaborate to produce two distinct gametes, one male and one female. The fusion of gametes results in the mixing of genetic material, resulting in the formation of a diploid cell with new combinations.