KEYWORDS
ASUAL
REPRODUCTION
BINARY FISSION
BUDDING
EGGS
EMBRYO
EXTERNAL
FERTILISATION
FERTILISATION
FOETUS
INTERNAL
FERTILISATION
METAMORPHOSIS
OVIPAROUS ANIMALS
SEXUAL
REPRODUCTION
SPERMB
VIVIPAROUS ANMALS
ZYGOTE
Answers
Answer:
Explanation:
D
o you recall the processes of
digestion, circulation and
respiration which you have
studied in your previous classes? These
processes are essential for the survival
of every individual. You have also learnt
about the process of reproduction in
plants. Reproduction is essential for the
continuation of a species. Imagine what
would have happened if organisms had
not reproduced. You will realise that
reproduction is very important as it
ensures the continuation of similar
kinds of individuals, generation after
generation.
You have already learnt in your
previous class about reproduction in
plants. In this chapter, we shall learn
how reproduction takes place in
animals.
9.1 Modes of Reproduction
Have you seen the young ones
of different animals? Try to name some
of the young ones by completing
Table 9.1 shown in examples at S. No.
1 and 5.
You must have seen the young
ones of various animals being born.
Can you tell how chicks and
caterpillars are born? How are kittens
and puppies born? Do you think that
these young ones looked the same
before they were born as they do now?
Let us find out.
Just as in plants, there are two modes
by which animals reproduce. These are:
(i) Sexual reproduction, and
(ii) Asexual reproduction.
9.2 Sexual Reproduction
Try to recall reproduction in plants
which you studied in Class VII. You will
remember that plants that reproduce
sexually have male and female
reproductive parts. Can you name these
parts? In animals also, males and
females have different reproductive parts
or organs. Like plants, the reproductive
parts in animals also produce gametes
that fuse to form a zygote. It is the zygote
which develops into a new individual.
This type of reproduction beginning
from the fusion of male and female
gametes is called sexual reproduction.
Let us find out the reproductive parts
Table 9.1
S. No. Animal Young one
1. Human Baby
2. Cat
3. Dog
4. Butterfly
5. Hen Chick
6. Cow
7. Frog
2019-2020
in humans and study the process of
reproduction in them.
Male Reproductive Organs
The male reproductive organs include a
pair of testes (singular, testis), two sperm
ducts and a penis (Fig. 9.1). The testes
produce the male gametes called
sperms. Millions of sperms are produced
by the testes. Look at Fig. 9.2 which
shows the picture of a sperm. Though
sperms are very small in size, each has
a head, a middle piece and a tail. Does
it appear to be a single cell? Indeed, each
sperm is a single cell with all the usual
cell components.
Fig. 9.1: Male reproductive
organs in humans
What purpose does the
tail in a sperm serve?
Fig. 9.3 : Female reproductive organs in
humans
Female Reproductive Organs
The female reproductive organs are a pair
of ovaries, oviducts (fallopian tubes) and
the uterus (Fig. 9.3). The ovary produces
Oviduct
Ovary
Uterus
Head
Middle piece
Tail
Fig. 9.2 : Human sperm
REPRODUCTION IN ANIMALS 101
Sperm