AP 10th Class Biology 7th Lesson Questions and Answers How do Organisms Reproduce?

AP State Board new syllabus AP Board Solutions Class 10 Biology 7th Lesson How do Organisms Reproduce? Questions and Answers.

10th Class Biology 7th Lesson How do Organisms Reproduce? Questions and Answers

10th Class Biology 7th Lesson Questions and Answers (Exercise)

Question 1.
Asexual reproduction takes place through budding in –
a) Amoeba
b) Yeast
c) Plasmodium
d) Leishmania
Answer:
b) Yeast

Question 2.
Which of the following is not a part of the female reproductive system in human beings ?
a) Ovary
b) Uterus
c) Vas deferens
d) Fallopian tube
Answer:
c) Vas deferens

Question 3.
The anther contains –
a) sepals
b) ovules
c) pistil
d) pollen grains
Answer:
d) pollen grains

Question 4.
What are the advantages of sexual reproduction over asexual reproduction?
Answer:
Advantages of sexual reproduction are :

• More variations are found in sexual reproduction.
• Survival of a species in a population is easy.
• Offspring has characteristics of both parents.
• It can lead to the formation of new species.
•  The chances of evolution increase.

Question 5.
What are the functions performed by the testis in human beings ?
Answer:
Testis has following three functions :

• It produces the male gametes called as sperm or spermatozoa.
• It synthesizes testosterone, the principal male sex hormone. That causes secondary sexual characters in men.
• It participates with the hypothalamus-pituitary unit in regulating reproductive function.

Question 6.
Why does menstruation occur ?
Answer:

• The ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg.
• Thus its lining becomes thick and spongy. This would be required for nourishing the embryo if fertilization had taken place.
• If the egg is not fertilized, it lives for about one day.Now, however, this lining is not needed any longer.
• So, the lining slowly breaks and comes out through the vagina as blood and mucous.
• This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.

Question 7.
Draw a labelled diagram of the longitudinal section of a flower.
Answer:

Question 8.
What are the different methods of contraception ?
Answer:

• Many ways have been devised to avoid pregnancy. These contraceptive methods fall in a number of categories.
• One category is the creation of a mechanical barrier so that sperm does not reach the egg. Condoms on the penis or similar coverings worn in the vagina can serve this purpose.
• Another category of contraceptives acts by changing the hormonal balance of the body so that eggs are not released and fertilization cannot occur. These drugs common need to be taken orally as pills. However, since they change hormonal balances, they can cause side-effects too.
• Other contraceptive devices such as the loop or the copper-T are placed in the uterus to prevent pregnancy. Again, they can cause side effects due to irritation of the uterus.
• If the vas deferens in the male is blocked, sperm transfer will be prevented. It is called vasectomy.
• If the fallopian tube in the female is blocked, the egg will not be able to reach the uterus. It is called tubectomy.
• In both cases fertilization will not take place. Surgical methods can be used to create such blocks.
• While surgical methods are safe in the long run, surgery itself can cause infections and other problems if not performed properly.

Question 9.
How are the modes for reproduction different in unicellular and multicellular organisms ?
Answer:
Reproduction in unicellular organisms can occur through various mechanisms, primarily asexual reproduction.

A sexual Reproduction :

1. Binary Fission : This is one of the most common methods of asexual reproduction in unicellular organisms. The cell replicates its DNA and then divides into two identical daughter cells. Bacteria,amoeba and many protists reproduce through binary fission.

2. Budding : In budding, a small outgrowth (bud) forms on the parent cell and eventually detaches to become a new individual. This method is observed in yeasts and hydra.

3. Fragmentation : Some unicellular organisms can reproduce through fragmentation, where the parent cell breaks into multiple fragments, and each fragment can grow into a new individual. Certain algae and protists use this method Ex : planaria.

Reproduction in multicellular organisms refers to the process by which these organisms create new individuals of the same species. There are two main types of reproduction in multicellular organisms: sexual reproduction and asexual reproduction.

Sexual Reproduction : Sexual reproduction involves the fusion of gametes from two parent organisms to produce offspring. This process promotes genetic diversity, which can be advantageous for the survival of a species in changing environments.

Question 10.
How does reproduction help in providing stability to populations of species ?
Answer:
Reproduction plays a crucial role in providing stability to populations of species through various mechanisms and strategies.

Replacement of individuals: Reproduction ensures that new individuals are constantly being born, replacing those that die due to predation, disease, accidents, or other factors. This replacement maintains the population size and prevents it from declining too rapidly.

Genetic diversity : Sexual reproduction brings diversity. This diversity is essential for the adaptation of species to changing environmental conditions and helps protect against the risks of inbreeding and genetic disorders.

Population regulation : Reproduction is often influenced by environmental factors such as resource availability, temperature, and predation. When resources are abundant and conditions are favorable, populations tend to grow.

Question 11.
What could be the reasons for adopting contraceptive methods ?
Answer:

• The sexual act always has the potential to lead to pregnancy.
• Pregnancy will make major demands on the body and the mind of the woman, and if she is not ready for it, her health will be adversely affected.
• Therefore, many ways have been devised to avoid pregnancy. Which are known as contraceptive methods.
• Some of these are temporary and permanent.

10th Class NS 7th Lesson Questions and Answers (InText)

Page No. 66

Question 1.
What is the importance of DNA copying in reproduction ?
Answer:

• Chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA.
• DNA means DeoxyriboNucleic Acid Molecules.
• The DNA in the cell nucleus is the information source for making proteins.
• If the information is changed, different proteins will be made.
• Different proteins will eventually lead to altered body designs.
• Therefore, a basic event in reproduction is the creation of a DNA copy.
• Cells use chemical reactions to build copies of their DNA.
• This creates two copies of the DNA in a reproducing cell, and they will need to be separated from each other.

Question 2.
Why is the variation beneficial to the species but not necessarily for the individual?
Answer:

• Variations are the result of genetic differences within a population.
• Variations play a crucial role in the evolution and survival of species. They are essential for the process of natural selection.
• For example, if there were a population of bacteria living in temperate waters, and if the water temperature were to be increased by global warming, most of these bacteria would die, but the few variants resistant to heat would survive and grow further. Variation is thus useful for the survival of species over time.

Page No. 72

Question 3.
How does binary fission differ from multiple fission?
Answer:

Binary fission	Multiple fission
In binary fission, a single parent cell divides into two identical daughter cells. It results in the formation of two offs-pring cells.	In multiple fission, a single parent cell divides into multiple daughter cells, often many more than two. This process can produce several offspring cells simultaneously.
Binary fission involves a single division of the parent cell into two daughter cells. It is a relatively simple process.	Multiple fission involves multiple rounds of division within the parent cell before the release of offspring cells. It is a more complex process.
The offspring cells produced through binary fission are generally of similar size to the parent cell.	In multiple fission, the offspring cells are often smaller in size compared to the parent cell due to the repeated rounds of division.
Binary fission is commonly observed in various unicellular organisms, such as bacteria and some protists.	Multiple fission is typically observed in certain protists like Plasmodium (the causative agent of malaria) and some algae.

Question 4.
How will an organism be benefited if it reproduces through spores ?
Answer:

• Spores are specialized reproductive structures produced by certain organisms, including fungi, plants, and some bacteria.
• Reproduction : Spores serve as a means of reproduction for the organisms that produce them. These structures that can give rise to new individuals when conditions are favorable.
• Dispersal : Spores are often well-suited for dispersal over long distances. They are small and lightweight, making them easily carried by the wind, water, or other environmental factors. This allows organisms to spread and colonize new areas.
• Survival in adverse conditions : Spores can withstand harsh environmental conditions, such as extreme temperatures, desiccation, and radiation. This ability to remain dormant and resilient helps the organisms survive adverse circumstances until conditions improve.

Question 5.
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer:

• Regeneration is the natural process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body parts to full function in plants and animals.
• This can seen in primitive organisms like hydra and can’t seen in complex organisms.
• Tissues in complex organisms cannot regenerate a replacement individual as they’re highly differentiated to perform specialized functions.
• Complex organisms aren’t made from simple and similar quiet cells, so it’s insufferable to regenerate. Regeneration can only happen in structure with similar cells.

Question 6.
Why is vegetative propagation practiced for growing some types of plants ?
Answer:
1. Vegetative reproduction is a method of asexual reproduction in plants where new individuals are produced from the vegetative parts of the parent plant, such as stems, roots, or leaves.

2. Plants practice vegetative reproduction for several reasons, and it offers them certain advantages in terms of survival, propagation, and adaptation.

3. Genetic continuity : Vegetative reproduction allows a plant to produce offspring that are genetically identical to the parent plant. This ensures the preservation of desirable traits and characteristics.

4. Rapid propagation : Vegetative reproduction is often faster than sexual reproduction, as it does not involve the development of seeds and the complexities of pollination and fertilization.

5. Adaptation to local conditions : Plants can adapt to local environmental conditions more effectively by producing clones of themselves through vegetative reproduction.

6. Vegetative repair and regeneration : Plants can use vegetative reproduction as a form of repair and regeneration. If a plant’s main stem or above-ground parts are damaged, it can often generate new shoots from the remaining healthy tissue.

7. This is a survival strategy that helps the plant recover and continue to grow.

8. Avoiding the need for pollinators : Many plants rely on pollinators like bees, butterflies, or wind to reproduce sexually. However, in cases where pollinators are scarce or unreliable, or in isolated habitats, vegetative reproduction can be a dependable means of reproduction.

Question 7.
Why is DNA copying an essential part of the process of reproduction ?
Answer:

• Chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA.
• DNA means Deoxyribo Nucleic Acid molecules. The DNA in the cell nucleus is the information source for making proteins.
• If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs.
• Therefore, a basic event in reproduction is the creation of a DNA copy.
• Cells use chemical reactions to build copies of their DNA: This creates two copies of the DNA in a reproducing cell, and they will need to be separated from each other.

Page No. 84

Question 8.
How is the process of pollination different from fertilization ?
Answer:
Pollination and fertilization are two essential processes in the reproduction of plants, particularly in the context of flowering plants (angiosperms). While they are related to plant reproduction, they are distinct stages in the process.

• Pollination is the transfer of pollen from the male reproductive part (anther) of a flower to the female reproductive part (stigma) of the same or a different flower.
• This transfer of pollen can occur through various means, including wind, water, insects, birds, and other pollinators. These agents are responsible for carrying the pollen grains to the female part of the flower.
• Pollination is a crucial step that brings the male and female reproductive structures of the flower into proximity, enabling the possibility of fertilization.

Fertilization :

• Fertilization is the process by which the male gametes (sperm cells in the pollen) combine with the female gametes (egg cells in the ovule) to form a zygote, which eventually develops into a new plant.
• After pollination has taken place and the pollen has landed on the stigma, a pollen tube may grow down to the ovule, allowing the sperm cells to reach the egg cells.
• Once the sperm cells successfully fertilize the egg cells, the zygote is formed, and this marks the beginning of the development of the embryo, which eventually grows into a new plant.

Question 9.
What is the role of the seminal vesicles and the prostate gland ?
Answer:
The seminal vesicles and the prostate gland are two important accessory glands of the male reproductive system, and they play essential roles in the production and transport of semen, which is the fluid that carries and nourishes sperm during ejaculation. Here’s a brief overview of the functions of each of these structures :

Seminal Vesicles :
Secretion of Seminal Fluid : The seminal vesicles are a pair of pouch-like structures located behind the bladder and contribute to the majority of the seminal fluid. This fluid makes up a significant portion of semen and provides nourishment, protection, and mobility for the sperm.

Prostate Gland :
Secretion of Prostatic Fluid : The prostate gland is a walnut-sized organ located just below the bladder and surrounds the urethra. It secretes a milky, slightly acidic fluid known as prostatic fluid, which makes up a significant part of the semen.

Question 10.
What are the changes seen in girls at the time of puberty ?
Answer:
Puberty is a natural and significant stage of development that occurs in both girls and boys as they transition from childhood to adolescence. During puberty, girls undergo a series of physical, emotional, and social changes. These changes are primarily driven by hormonal shifts, particularly an increase in estrogen.

• Breast development: One of the earliest signs of puberty in girls is the development of breast tissue.
• Growth spurt : Girls experience a rapid increase in height during puberty. This growth spurt can vary in timing and duration but usually occurs around the age of 9-14.
• Menstruation : Menstruation, or the onset of the menstrual cycle, marks a significant event in a girl’s puberty. This typically begins around the age of 10-16.
• Pubic and underarm hair : Girls develop pubic hair and underarm hair as a result of increased androgen hormones during puberty.
• Changes in body shape : As girls go through puberty, their bodies undergo changes in fat distribution.
• Acne and skin changes : Hormonal fluctuations can lead to skin changes, including an increased likelihood of acne. Skin may also become oilier during this time.
• Emotional and psychological changes : Puberty can bring about mood swings, increased emotional sensitivity, and a desire for independence.
• Development of secondary sexual characteristics : In addition to breast development, girls also develop other secondary sexual characteristics, such as the widening of the pelvis.
• Voice changes: Unlike boys, girls typically do not experience a significant deepening of their voices during puberty.

Question 11.
How does the embryo get nourishment inside the mother’s body ?
Answer:

• The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta.
• This is a disc which is embedded in the uterine wall. It contains villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi.
• This provides a large surface area for glucose and oxygen to pass from the mother to the embryo.
• The developing embryo will also generate waste substances which can be removed by transferring them into the mother’s blood through the placenta.
• The development of the child inside the mother’s body takes approximately nine months.
• The child is born as a result of rhythmic contractions of the muscles in the uterus.

Question 12.
If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases ?
Answer:

• Copper – T, also known as intrauterine device (IUD) with copper, is a form of longacting reversible contraception that is inserted into the uterus to prevent pregnancy.
• Copper – T does not protect against sexually transmitted diseases (STDs) or infections.
• Who are sexually active and want to protect themselves from both unintended pregnancies and STDs, it’s important to use barrier methods like condoms in addition to other forms of contraception like Copper T.
• Condoms provide a physical barrier that can help reduce the risk of STD transmission when used correctly.

AP Board Solutions Class 10 Biology Chapter 7 Questions and Answers (Lab Activities)

Activity – 7.1

1. Write an activity to show the procedure of budding in yeast cells.

• Dissolve about 10 g . of sugar in 100 ml of water.
• Take 20 ml of this solution in a test tube and add a pinch of yeast granules to it.
• Put a cotton plug on the mouth of the test tube and keep it in a warm place.
• After 1 or 2 hours, put a small drop of yeast culture from the test tube on a slide and cover it with a coverslip.
• Observe the slide under a microscope.

Observation :

• We found small round bodies that are unicellular yeast that have bulges. These are called buds.
• The buds prolong and divide into new individuals.
• This type of asexual reproduction is called budding.

Activity – 7.2

2. How do you observe the growth of mould on the slice of bread?

• Wet a slice of bread, and keep it in a cool, moist and dark place.
• Observe the surface of the slice with a magnifying glass.
• Record your observations for a week.

Observations :

• First two days I can’t found anything clearly.
• After two days I found thread like white structures on the bread.
• Later I found that it is growing in that area.
• It appear a white mold even to naked eye.
• Later it become dark in colour.
• In microscope I found small round bodies called as spores.
• Spores are asexual reproduction modes in fungi.

Activity – 7.3

3. Examine and comparision the structure of Amoeba.

• Observe a permanent slide of Amoeba under a microscope.
• Similarly observe another permanent slide of Amoeba showing binary fission.
• Now, compare the observations of both the slides.

Observations :

• I found that in the slide of binary fission the amoeba is prolonged.
• The nucleus is divided into two.
• The amoeba appears as two poisons.
• These changes can’t seen in permanent slide of amoeba.

Activity – 7.4

4. Conduct an activity to observe the fragmentation.

• Collect water from a lake or pond that appears dark green and contains filamentous structures.
• Put one or two filaments on a slide.
• Put a drop of glycerine on these filaments and cover it with a coverslip.
• Observe the slide under a microscope.
• Can you identify different tissues in the Spirogyra filaments ?
  No, the filament contain multi cells but all are in similar. I can’t find any tissue in this spirogyra filament.

Activity – 7.5

5. Write an activity how the a sexual reproduction occur in Pi sato.

• Take a potato and observe its surface. Can notches be seen? Yes potato surface contain notches these are called as eyes.
• Cut the potato into small pieces such that some pieces contain a notch or bud and some do not.
• Spread some cotton on a tray and wet it. Place the potato pieces on this cotton. Note where the pieces with the buds are placed. The pieces which have notches have buds.
• Observe changes taking place in these potato pieces over the next few days. Make sure that the cotton is kept moistened.
• Potato pieces that have notches are growth and form a new plant.
  The pieces which does not have growth which does not have any notches
• Which are the potato pieces that give rise to fresh green shoots and roots? Potato pieces that have notches are growth and form a new plant with shoot and root.

Activity – 7.6

6. How does leaves represent vegetative propagation?

• Select a money-plant.
• Cut some pieces such that they contain at least one leaf.
• Cut out some other portions between two leaves.
• Dip one end of all the pieces in water and observe over the next few days.
• Which ones grow and give rise to fresh leaves?
  The pieces that contain leaf give rise to new leaf
• What can you conclude from your observations?
  The portion between two leaves is called as inter node. This region can’t produce any roots or leaves. So it can’t show vegetative propagation.

Activity – 7.7

7. Write an activity to observe cotyledons of the seed.

• Soak a few seeds of Bengal gram (chana) and keep them overnight.
• Drain the excess water and cover the seeds with a wet cloth and leave them for a day. Make sure that the seeds do not become dry.
• Cut open the seeds carefully and observe the different parts.
• Compare your observations with the Figure and see if you can identify all the parts.

Observations :

• I found a long white thread germination from each seed.
• Its nothing but a root in the diagram it is shown as radical.
• When I open the seeds I also found small plant which one call as plumule.
• All my observations are matched to diagram.