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SCIENCE 6.
UNIT 3. HUMAN REPRODUCTION.
CONTENTS: 1.– Changes on the body. Puberty: Secondary sex characteristics. 2.– Male reproductive system. 3.– Female reproductive system. 4.– Reproductive cells. Male cells—Female cells. Menstrual cycle. 5.– Fertilisation and pregnancy. 6.– Childbirth.
Reproduction is one of the vital function that living beings do. All living beings can produce more beings similar to themselves, so human beings can also produce more human beings similar to them. In nature, there are two kinds of reproduction: asexual reproduction and sexual reproduction. a.– Asexual reproduction: when only one individual produces new living beings on its own (descendents). The new living being inherits only the genes from that parent. b.– Sexual reproduction: when a male and a female produce new living beings. The new living being inherits genes from both, its mother and its father. 1.– CHANGES ON THE BODY IN PUBERTY: SECONDARY SEXUAL CHARACTERISTICS. Before the moment a baby is born, reproductive organs of boys and girls are different. These differences from males and females are called primary sexual characteristics.
C.E.I.P. SANTA ANA (Madridejos)
HUMAN REPRODUCTION is the process in which human beings produce more human beings similar to themselves. Human reproduction is sexual. A male and a female produce a new baby.
On a baby, you can distinguish his/her primary sexual characteristics: his/her reproductive organs.
Secondary sexual characteristics are features that distinguish the two sexes, but that are not directly part of the reproductive system.
Secondary sexual characteristics are changes in boys and girls during the adolescence or puberty. Puberty is a period of time when a child’s body changes into an adult body (from 11 to 18 year for girls, and from 13 till 18 for boys ). There are physical and psychological changes, and its reproductive system reach maturity. Sexual glands produce hormones. Males produce testosterone and females oestrogen that control these changes. Boys and girls:
.- Appearance of pubic and armpit hair for boys and girls.
Boys: .- Adam’s apple is visible and voice gets lower. .– Shoulders get broader and muscle development. .– Hair on the face, body, arms and legs appears. .- Testicles mature and produce sperm.
MALE
Facial hair
Adam’s apple
Broad shoulders armpit
Girls: .– Breasts development. .– Hips widen. .– The first menstrual cycle comes.
FEMALE Breasts development
Increase of hair on body, arms and legs Pubic hair
Mature genital organs Muscle development
1 Widen hips
Pubic hair
USEFUL WORDS: .– sexual reproduction .– asexual reproduction .– primary sexual characteristics .– secondary sexual characteristics .– adolescence .– puberty .– hormones