Chapter 2 – (D) Growth And Development | Life Science Solution Class 10

1. Cell division,
2. Cell elongation, 
3. Cell differentiation,
4. Cell maturation.

1. Light, 
2. Temperature, 
3. Enzymes, 
4. Carbon dioxide.

1. Magnesium, 
2. Calcium, 
3. Phosphorus,
4. None of the above.

Question

1. An increase in dry weight accompanied by an increase in the size and volume of the living organism is called ___.
2. The capacity to replace damaged or lost parts is termed as do not grow without sunlight and is called ___.
3. Plants which do not grow without sunlight are called ___.
4. Plants that avoid sunlight are called ___.
5. Due to growth ___ weight of the body increases.
6. A period showing declination of growth results in growing old is called ___.
7. ageing occurs due to the accumulation of ___ ___ within the organ of living organisms.
8. The branch of biology concerned with studying ageing is known as ___.

Answer

1. Growth
2. Regeneration
3. Phototropic
4. Skototropic
5. Dry
6. Senescence
7. Damage products
8. Gerontology

Write ‘True’ or ‘False’

Question

1. Growth is an increase is dry weight accompanied by an increase in the size and volume of the living organism.
2. The second phase of growth is the phase of cell division.
3. The capacity to replace damaged lost parts is termed regeneration.
4. The changes in the body or body parts due to ageing that lead to a decreasing life expectancy are known as senescence.
5. The science that deals with the study of ageing to called gerontology.
6. Ageing does not affect the heart and kidneys.

Answer

1. True; Growth is the process of an increase in dry weight along with an increase in the size and volume of the living organism.
2. True; The second phase of growth is cell division, during which time the number of cells in the organism increases.
3. True; The capacity to replace damaged or lost parts is termed regeneration, which is an essential aspect of Growth And Development in many organisms.
4. True; Senescence refers to the changes in the body or body parts due to ageing that lead to a decreasing life expectancy.
5. True; The science that deals with the study of ageing is called gerontology, and it encompasses the biological, psychological, and social aspects of ageing.
6. False; ageing can affect the heart, kidneys, and other organs in the body, leading to a decline in their function over time.

Very Short Answer (VSA) type questions

Question 1

What is growth? 

Answer

Question 2

Answer

Development refers to the series of changes that occur during an organism’s life cycle, resulting in the emergence of new structures, functions, and behaviours.

Question 3

Mention the significance of growth.

Answer

Growth is essential for the survival of organisms as it allows them to acquire necessary resources and adapt to changing environments.

Question 4

What do you mean by regenerative growth? 

Answer

Regenerative growth refers to the ability of an organism to replace damaged or lost tissues or organs through the proliferation of existing cells or the differentiation of stem cells.

Question 5

Name the hormones that help plant growth. 

Answer

Question 6

Mention the different phases of plant growth. 

Answer

The different phases of plant growth are:

1. Cell division
2. Cell enlargement
3. Cell differentiation

Question 7

Name two factors, one external and another internal which are responsible for plant growth.

Answer

1. External factor – Light
2. Internal factor – Hormones

Question 8

What do you mean by senescence and ageing?

Answer

Senescence and ageing refer to the natural process of decline and deterioration that occurs in living organisms over time, resulting in decreased physiological functions and eventual death.

Question 9

Mention the first two phases of growth. 

Answer

The first two phases of growth are:

1. Cell division
2. Cell enlargement

Question 10

Answer

1. Light
2. Temperature

Question 11

Mention two internal factors of growth. 

Answer

1. Hormones
2. Genes

Question 12

Give one example of heterometabolic metamorphosis. 

Answer

Butterfly.

Question 13

Mention one example of homometabolic metamorphosis. 

Answer

Question 14

Name two hormones which takes part in metamorphosis. 

Answer

1. Juvenile hormone
2. Ecdysone

Question 15

Which hormone helps in the absorption of the tail of the tadpole? 

Answer

Thyroid hormone (TH)

Question 16

Name two phytohormones which promote senescence. 

Answer

1. Ethylene
2. Abscisic acid

Question 17

Name the branch of developmental biology concerned with the study of ageing. 

Answer

The branch of developmental biology concerned with the study of ageing is called “gerontology”.

Question 18

Mention two factors affecting senescence and ageing. 

Answer

1. Genetics
2. Environment

Question 19

Name the hormone which acts as a chemical signal for intraspecific communication. 

Answer

The hormone which acts as a chemical signal for intraspecific communication is called “pheromones”.

Question 20

Name one plant hormone that influences growth. 

Answer

Auxin

Question 21

Name one short-day plant. 

Answer

One example of a short-day plant is the poinsettia (Euphorbia pulcherrima).

Question 22

Name one long day plant.

Answer

One example of a long day plant is spinach (Spinacia oleracea).

Short Answer (SA) type questions

Question 1

Write about the different phases of growth. 

Answer

The growth of a plant can be divided into three main phases: cell division, cell enlargement, and cell differentiation.

1. Cell division: The phase of active cell division and proliferation by mitosis, leading to an increase in cell number.
2. Cell enlargement: The phase where cells elongate and expand, leading to an increase in overall plant size, regulated by the hormone auxin.
3. Cell differentiation: The phase where cells specialize and acquire specific functions, forming different types of tissues and organs, influenced by genes, hormones, and environmental factors.

Question 2

Write about the different factors in connection with the senescence and ageing of plants and animals. 

Answer

Some of the factors that can affect senescence and ageing in plants and animals include:

1. Genetics – Genetic factors play a role in determining lifespan and ageing in organisms.
2. Environment – External factors such as temperature, light, nutrition, and stress can affect senescence and ageing.
3. Hormones – Hormones such as ethylene, abscisic acid, and cytokinins influence senescence by regulating physiological processes.
4. Oxidative stress – Imbalance between reactive oxygen species and antioxidant defences can accelerate ageing.

Question 3

Write in brief about the senescence in Animals. 

Answer

Here are some key points about senescence in animals:

1. ageing is a natural process that occurs in all animals and is influenced by a range of factors such as genetics, environment, and lifestyle.
2. Senescence involves a gradual decline in physiological functions such as metabolism, immune function, and hormonal regulation.
3. Cellular changes associated with senescence include telomere shortening, DNA damage, and protein aggregation.
4. Age-related diseases such as cancer, neurodegeneration, and cardiovascular disease are more common in older animals.
5. The ageing process is influenced by both genetic and environmental factors, with some species living much longer than others.

Question 4

Name the five phases of human development.

Answer

The five phases of human development

1. Infancy
2. childhood
3. Adolescence
4. Adulthood
5. Senescence

Question 5

Differentiate between Plant growth and Animal growth. 

Question 6

Differentiate between Growth And Development.

Answer

Long Answer (LA) type questions

Question 1

(a) Define Growth. (b) Name the different phases of plant growth. 

Answer

Question 2

Describe the role of different factors affecting growth. 

Answer

There are many different factors that can affect growth in organisms, including:

1. Genetics: The genetic makeup of an organism can play a significant role in determining its growth patterns, such as the size and shape of its body, as well as its susceptibility to certain diseases.
2. Environment: Environmental factors such as temperature, humidity, light, and nutrients can all influence growth, as well as factors like stress and exposure to toxins.
3. Hormones: Hormones play a critical role in regulating growth by controlling processes such as cell division, differentiation, and elongation.
4. Oxidative stress: This is a type of cellular damage that can occur as a result of environmental stressors, and can have a negative impact on Growth And Development.
5. Cellular signalling: Different signalling pathways within cells and tissues can interact to regulate Growth And Development.

Question 3

(a) What is ageing? (b) Describe the various morphological and physiological changes that occur in humans during ageing.

Answer

(a) ageing refers to the gradual decline in physiological and cellular functions that occurs over time in many organisms, including humans. This process can be influenced by genetic and environmental factors and can lead to a range of age-related diseases and disorders.

(b) Some of the morphological and physiological changes that occur during ageing in humans include:

1. Loss of muscle mass and strength can lead to decreased mobility and increased risk of falls.
2. Decreased bone density, leads to osteoporosis and increased risk of fractures.
3. Decline in cognitive function, including memory, attention, and processing speed.

Question 4

Define five phases of human development.

Answer

The five phases of human development are:

1. Infancy: This phase covers the period from birth to approximately 2 years of age, during which time infants go through rapid physical and cognitive development.
2. Childhood: This phase covers the period from approximately 2 to 12 years of age, during which time children continue to grow and develop physically and cognitively, and become more independent and social.
3. Adolescence: This phase covers the period from approximately 12 to 18 years of age, during which time individuals undergo significant physical and emotional changes, and begin to establish their identities and independence.
4. Adulthood: This phase covers the period from approximately 18 years of age onwards, during which time individuals continue to develop and mature, and may experience major life events such as starting a career, getting married, and having children.
5. Senescence: This phase covers the period of decline that occurs in older adulthood, which may include changes in physical and cognitive function and increased risk of diseases such as cancer and dementia.