Life Processes class 10 solutions 2020

Chapter - 3.0

Part - 2

Life Process in Living Organisms Part – 2

Sexual Reproduction:-

Sexual reproduction always occurs with the help of two germ cells.

1 Female Gamete

2 Male Gamete are those two germ cells.

 

1 Gamete formation:- Gametes are formed by the meiosis. In meiosis, chromosome number is reduced to half Hence haploid gametes are formed.

2 Fertilization:- A diploid zygote is formed in this process by union of haploid male and female gamete.

• Embryo develops to from new individual
• Male parent and female parent are involved in this type
• Diversity in living organisms occurs due to genetic variation.
• Genetic variation help the organisms to adjust in changing environment

A – Sexual Reproduction in plants:-

• Four  floral whorls as calyx, corolla, androecium and gynoecium.
• They perform the function of reproduction.
• Androceium present – Male flower.
• Gynoecium present – Female flower. (eg. Papaya )
• Flowers having stalk – Sessile
• Androecium male whorl – stamens.

 

• Gynoecium female whorl – carpel
• Pollen grains transferred to the stigma (Pollination)
• Pollen tube carries male gametes
• Pollen tube reaches Embryo sac via style.
• Male gametes units with egg cell to from zygote.
• Two nuclei participate in this process is called double fertilization.

 

B – Sexual reproduction in Human being:-

• Men have XY Sex Chromosomes.
• Women have XX chromosomes.
• Reproductive system with specific organ develops in the body of men and women due to sex chromosomes

1) – Human male reproductive system.

2) – Human female reproductive system.

Gamete formation:-

• Sperm and ovum are formed by meiosis.
• Sperm are produced in testes of men from maturation till death
• While in female and oocytes mature every month from maturity up to the age of menopause – 45 years of age

Fertilization:-

• Formation of zygote by union of sperm and ovum is called as fertilization.
• Journey by the route of vagina – uterus – oviduct.

 

Development and Birth:-

Menstrual Cycle:-

• Female reproductive system undergo changes at puberty at the interval of every 28 – 30 days.
• These repetitive changes are called as menstrual cycle.
• It is a natural process controlled by four hormones.

Four Hormones –

• Follicle Stimulating hormone (FSH)
• Luteinizing hormone (LH)
• Estrogen
• Progesterone

 

Reproduction and Modern Technology:-

• In Vitro Fertilization (IVF)
• Surrogacy
• Sperm Bank /Semen Bank

Twins:-

• Two embryos develop simultaneously  in the same uterus.
• Thus two off springs are delivered simultaneously
• There are two types of twins
• Monozygotic  twins and dizygotic twins.