CBSE Questions for Class 10 Biology How Do Organisms Reproduce Quiz 4 - MCQExams.com

Sepals form the outermost whorl of a flower. They are mostly green in colour due to the presence of chlorophyll and hence can perform photosynthesis and may supply food to other floral parts. 

So, the correct answer is A - 'Sepals'.

Solution

Correct answer is option D.

Explanation for correct option:

• Menstruation is cyclic discharge of unfertilised egg, debris, tissues from uterus along with blood.   
• If egg is fertilized, it travels to the uterus over the following 6–12 days, to possibly implant for pregnancy.
• If there is no fertilization- levels of oestrogen and progesterone drops – resulting in breaking down of uterine lining i.e., menstruation. And level of LH, FSH rises to start new cycle.

• Once a girl starts menstruation, her body needs more iron to make up for the amount of iron that is lost in their menstrual cycle. 
• During menstruation, blood flows out from the body after a fixed interval. 
• As we know haemoglobin is composed of a protein called globulin, four heme groups, each associated with an iron atom. 
• In the absence of iron, the person becomes anaemic. So, to avoid this condition in females, it is necessary to take more iron.

• The human voice has many components and the pitch is an integral part of the human voice. The pitch of the voice is defined as the 'rate of vibration of the vocal folds'. 
• The sound of the voice changes as the rate of vibrations varies. As the number of vibrations per second increases, so does the pitch, meaning the voice would sound higher. 
• Faster rates from higher voices or higher pitches while slower rate elicits deeper voices or lower pitches. The vibrations and the speed at which they vibrate are dependent on the length and thickness of vocal cords. 
• Women tend to have higher voices or higher pitches than men do because they have shorter vocal cords.

• Hydra is an aquatic animal that reproduces both sexually and asexually.  When plenty of food is available Hydra undergoes an asexual mode of reproduction by producing a small outgrowth called 'bud' on its body. This type of asexual reproduction is called budding. The bud stays attached to the parent body and keeps growing. Once this bud matures, it breaks off from the parent body and grows individually as a new individual.
• Amoeba and Paramecium undergo fission, where the parent cell splits into two daughter cells.
  
• Plasmodium exhibits multiple fission, where many daughter cells are produced.
  

So, the correct answer is option A.

• Binary fission is a type of asexual reproduction in which a single organism becomes two independent organisms.
• In some organisms like an amoeba, during cell division, the cell splits into two in any plane.
• In some other organisms, binary fission occurs in a definite plane. For e.g. Leishmania 
• So, the correct answer is 'Leishmania'.

• The first and second whorl of a flower consists of sepals and petals, respectively.
• The androecium is the third whorl of a flower. Each unit is called stamen. It is the male reproductive organ of the flower. A stamen is made up of a stalk called the filament and an anther. 
• The fourth whorl, however, is comprised of the female reproductive structure called gynoecium. Each unit is called carpel/pistil.

• Fertilization is the process of fusion of male and female gametes to form the zygote. The process of fusion takes place in the fallopian tube/oviduct of the female reproductive tract. 
• The egg released by the ovary travels to the fallopian tube and remains there for around 24 hours. 
• The sperm traveling up to the fallopian tube can fertilize the egg while it is still present there.

$$\textbf{Correct option:A}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ Those flowers which possess both male reproductive entity stamens and female reproductive organ pistil within the same inflorescence eg;lily, rose etc. are known as Bisexual flowers.

$$\textbf{Option (B)}$$

$$\bullet$$ Those flowers which homes only any one reproductive part either a stamen or a carpel are known as unisexual flowers. Each flower is either staminate (having only functional stamens) and thus "male" or  carpellate (or "pistillate") (having only functional carpels) and thus "female" eg; papaya, watermelon, cucumber, maize etc.

$$\textbf{Option (C)}$$

$$\bullet$$ Dioecious plants are those which have different male and female flowers on entirely different plants . So not only does the plant have separate male/female flowers, they have male plants (with only male flowers) and female plants (with only female flowers) eg; hollies and asparagus are dioecious.

$$\textbf{Option (D)}$$

$$\bullet$$ A flower which lacks any of these parts; sepals, petals, stamens, pistil is said to be incomplete flower.  Stamens and pistils are not present together in all flowers eg; squash, sweet corn etc.

$$\textbf{Hence, the correct option is (A)}$$