Assignment Code: BZYCT-133/TMA/2023

Course Code: BZYCT-133

Assignment Name: Comparative Anatomy and Developmental Biology of Vertebrates

Year: 2023

Verification Status: Verified by Professor

Note: Attempt all questions. The marks for each question are indicated against it.

Part-A

Q1ia) Which are the four successive layers present in the integument of mammals? (1)

Ans) The four successive layers of the integument of mammals, from outermost to innermost, are:

Stratum corneum, Epidermis, Dermis, Hypodermis.

Q1ib) Which muscle is attached to the hair follicle of human beings and make hair stand erect? (1)

Ans) The muscle that is attached to the hair follicle of humans and causes the hair to stand erect is called the arrector pili muscle.

Q1ii) What are the different types of feathers? What are their functions? (3)

Ans) There are several different types of feathers found on birds, each with a unique function. These feather types include:

1. Contour Feathers: These are the most common feathers on a bird's body and are responsible for giving the bird its shape and providing insulation. They are also essential for flight, as they create the smooth, streamlined shape needed for efficient movement through the air.

2. Flight Feathers: These are specialized contour feathers found on the wings and tail of birds. They are responsible for generating lift and propulsion during flight.

3. Down Feathers: These are small, fluffy feathers that provide insulation and help to maintain body heat. They are found under the contour feathers and provide an extra layer of warmth.

4. Semiplume Feathers: These are intermediate in size between contour and down feathers and are found beneath the contour feathers. They provide insulation and help to fill out the bird's body shape.

5. Filoplume Feathers: These are small, hair-like feathers that are found near the base of contour feathers. They are thought to be involved in sensory functions, providing information about feather position and movement.

6. Bristle Feathers: These are stiff, hair-like feathers found around the eyes, beak, and mouth of birds. They help to protect these sensitive areas and may also play a role in sensing prey.

Q1iii) Choose the correct alternative: (5)

i) The visceral skeleton is also referred to as (chondrocranium/ splanchnocranium).

Ans) Splanchnocranium.

ii) Jaws arose from the (mandibular/hyoid) arch.

Ans) Mandibular arch.

iii) The upper jaw is made up of the (palatoquadrate/Meckel’s cartilage).

Ans) Palatoquadrate cartilage.

iv) Branchial basket formed of the visceral arches is found in (teleosts/cyclostomes).

Ans) Cyclostomes.

v) If the jaw is attached to the skull and not suspended by the hyomandibula, the suspensorium is (Autodiastylic/Autostylic).

Ans) Autostylic.

Q2) Fill in the blanks. (10)

i) The four types of mammalian uteri are …………………., ………………………., ……………. and …………………….

Ans) The four types of mammalian uteri are duplex, bipartite, bicornuate, and simplex.

ii) The muscle layer of the uterus is called ………………………….

Ans) The muscle layer of the uterus is called the myometrium.

iii) The sequence of organs of mammalian female genital system are:

two ovaries →………….……… …………..…… →……………… →………………

Ans) The sequence of organs of the mammalian female genital system are:

Two ovaries → two oviducts →uterus →cervix→ vagina.

iv) In female birds only the …………………… gonad develops into the ovary.

Ans) In female birds, only the left gonad develops into the ovary.

Q3i) List the primary divisions of the nervous system and their subdivisions. (5)

Ans) The nervous system is made up of many different types of cells, tissues, and organs that work together to coordinate and control how the body works. It has two main parts: the CNS (central nervous system) and the PNS (peripheral nervous system) (PNS).

Central Nervous System (CNS)

CNS is brain and spinal cord. The skull and spinal column shield the brain and spinal cord. Brain controls body. It integrates sensory information, starts and coordinates voluntary and involuntary actions, and governs many of the body's vital functions, such as breathing and heart rate. From the brain to the lower back, the spinal cord is thin and lengthy. It sends sensory data to the brain and motor commands to the muscles.

The CNS can be further subdivided into three main parts:

1. Brainstem: The midbrain, pons, and medulla oblongata make up the brainstem. The brainstem is at the base of the brain. It controls many of the automatic functions of the body, like breathing, heart rate, and blood pressure.

2. Cerebellum: The cerebellum is located behind the brainstem. It oversees coordinating and controlling voluntary movements, such as posture, balance, and coordination.

3. Cerebrum: The cerebrum is the biggest part of the brain. It processes and makes sense of sensory information, starts and coordinates voluntary movements, and controls many of the body's most important functions.

Peripheral Nervous System (PNS)

1. Nerves and ganglia outside the CNS form the PNS. It manages central nervous system-body communication. The PNS has two major parts:

2. Somatic Nervous System: The somatic nervous system oversees voluntary movements and sends information from the skin, muscles, and joints to the central nervous system.

3. Autonomic Nervous System: The autonomic nervous system controls things like breathing, heart rate, and digestion that you don't have to think about. It can be broken down even further into two parts:

i) Sympathetic Nervous System: The sympathetic nervous system gets the body ready to "fight or flight" by speeding up the heart rate, making the pupils bigger, and slowing down digestion and other non-essential processes.

ii) Parasympathetic Nervous System: The parasympathetic nervous system helps you "rest and digest" by slowing down your heart rate, making your pupils smaller, and helping with digestion and other non-essential functions.

Q3ii) List the cranial nerves of special senses and the nerves that innervate the eye muscles. (5)

Ans) The cranial nerves are a group of 12 nerve pairs that come from the brain and control different parts of the head, neck, and trunk. Some of these have to do with special senses and how the eyes move.

Cranial Nerves of Special Senses

1. Olfactory nerve (I): The olfactory nerve is responsible for the sense of smell.

2. Optic nerve (II): The optic nerve is responsible for vision and carries information from the retina to the brain.

3. Vestibulocochlear nerve (VIII): The vestibulocochlear nerve is responsible for hearing and balance.

Nerves that Innervate the Eye Muscles

1. Oculomotor nerve (III): The oculomotor nerve innervates the superior rectus, inferior rectus, medial rectus, and inferior oblique muscles of the eye, which are responsible for most of the eye's movements.

2. Trochlear nerve (IV): The trochlear nerve innervates the superior oblique muscle of the eye, which helps to move the eye downward and outward.

3. Abducens nerve (VI): The abducens nerve innervates the lateral rectus muscle of the eye, which helps to move the eye outward.

The three nerves we talked about above (III, IV, and VI) control how the eye moves. These nerves are called the extraocular muscles. The eye and the area around it are also sensed by the ophthalmic nerve (V1) of the trigeminal nerve. The facial nerve (VII) is involved in lacrimation (tear production) and taste sensation in the front two-thirds of the tongue.

Q4) Describe specialised sensory organs of vertebrates and relate their role to their habitat. (10)

Ans) Vertebrates have a variety of specialised organs that help them sense and respond to different things in their environment. These sense organs are very important for helping vertebrates live and do well in their own environments.

Vision: Vision is one of the most important senses for vertebrates, and the eyes are the main organs for this sense. Different types of eyes have developed in vertebrates to fit their environments and ways of life. For instance, animals that hunt for food like eagles and hawks have sharp eyesight and a high level of acuity, which lets them see their prey from a long way away. Bats and other animals that live in dark places have developed echolocation, which lets them "see" their surroundings by using sound waves. Fish, amphibians, reptiles, and mammals that live in water have eyes that work well underwater. Some of these animals have also evolved a third eyelid to protect their eyes while they swim.

Hearing: Hearing is also important for a lot of vertebrates, especially those that are active at night or live in places with a lot of noise. Vertebrates have specialised organs, like ears, for hearing. The structure of these organs depends on where the animal lives. For example, animals that live in water, like whales and dolphins, have ears that can pick up sound waves through water. Animals that live on land, like humans and dogs, have ears that can pick up sound waves in the air. Some animals, like snakes, have developed organs that can "hear" vibrations. They use these organs to hear moving prey.

Smell: Smell is an important sense for many vertebrates, especially those that use it to hunt or find predators. Vertebrates have developed organs that are just for smelling, like the olfactory epithelium in the nose, which can pick up on the smell of doors in the air. Some animals, like snakes, have a special organ in the roof of their mouths called the Jacobson's organ. This organ can sense chemicals in the air or on the ground.

Taste: Smell is an important sense for many vertebrates, especially those that use it to hunt or find predators. Vertebrates have developed organs that are just for smelling, like the olfactory epithelium in the nose, which can pick up on the smell of doors in the air. Some animals, like snakes, have a special organ in the roof of their mouths called the Jacobson's organ. This organ can sense chemicals in the air or on the ground.

Touch: Many vertebrates, especially those that live in complex environments or must move through tight spaces, need to be able to feel things. Vertebrates, like cats and seals, have specialised touch organs, like whiskers, that help them feel vibrations in the environment and move through tight spaces. Some animals, like fish, have a special organ called the lateral line that runs along their body and senses changes in water pressure. This lets them know when something is moving in the water.

Q5) Briefly write the functions of the following hormones secreted in mammals. (10)

a) Adrenocoricotropic hormone

Ans) Adrenocorticotropic hormone (ACTH) is a hormone made by the anterior pituitary gland. It is a very important part of how the adrenal glands release cortisol. Here are the main things that ACTH does:

1. Stimulating Cortisol Production: ACTH stimulates adrenal cortisol production. Cortisol, a steroid hormone, regulates stress, metabolism, immune system, and blood pressure. ACTH helps maintain homeostasis by stimulating adrenal cortex cortisol production.

2. Modulating the Stress Response: Stress releases ACTH, which controls stress response. ACTH boosts energy and suppresses the immune system via increasing cortisol production. ACTH reduces stress and stabilises the body.

3. Regulating the Circadian Rhythm: Circadian rhythms release ACTH. Morning levels are greatest and drop throughout the day. This maintains the body's circadian clock and sleep-wake cycle.

4. Regulating Melanin Production: ACTH regulates melanin, which colours skin, hair, and eyes. ACTH protects the skin's natural colour and UV radiation by increasing melanin production.

b) Parathormone

Ans) The parathyroid glands produce parathormone (PTH). Maintaining blood calcium and phosphorus is crucial. Most important parathormone functions:

1. Regulating Calcium Levels: PTH regulates blood calcium. PTH makes bones release more calcium, intestines absorb more calcium, and kidneys excrete less calcium. PTH regulates blood calcium, which is essential for many physiological functions.

2. Regulating Phosphorus Levels: PTH regulates blood phosphorus. PTH increases phosphorus excretion by the kidneys, balancing blood calcium and phosphorus.

3. Regulating Vitamin D Metabolism: PTH increases kidney vitamin D production, which regulates intestinal calcium and phosphorus absorption. Vitamin D helps bones and the immune system.

4. Maintaining BONE HEALTH: PTH helps bones break down and repair. PTH maintains blood calcium levels by releasing calcium from the bones.

c) Aldosterone

Ans) Aldosterone is a steroid hormone made by the adrenal glands. It helps keep the electrolyte balance and blood pressure in the body in check. Here are the most important things aldosterone does:

1. Regulating Sodium Levels: The main job of aldosterone is to control how much sodium is in the body. Aldosterone makes the kidneys take more sodium back in and helps the body hold on to more sodium. This helps keep the amount of sodium in the blood steady, which is important for many bodily functions.

2. Regulating Potassium Levels: Aldosterone also has something to do with how much potassium is in the body. Aldosterone helps keep a balance between sodium and potassium in the body by making the kidneys get rid of more potassium.

3. Regulating Blood Pressure: Aldosterone helps keep blood pressure in check by making the kidneys take in more sodium. By increasing the amount of sodium in the blood, aldosterone promotes the retention of water, which increases blood volume and helps maintain blood pressure.

4. Maintaining Acid-base Balance: Aldosterone helps keep the acid-base balance in the body stable by controlling how the kidneys get rid of hydrogen ions. Aldosterone helps keep the blood's pH steady by making more hydrogen ions leave the body.

d) Testosterone

Ans) Testosterone is a steroid hormone that is mostly made by men's testes and, in smaller amounts, by women's ovaries. It is very important for the development and maintenance of men's reproductive organs and secondary sexual traits. Here are the most important things that testosterone does:

1. Developing Male Reproductive Organs: Testosterone is a very important part of how male reproductive organs like the penis, testes, and prostate gland grow and work. It also helps the body make more sperm.

2. Developing Secondary Sexual Characteristics: Testosterone is the hormone that causes secondary sexual traits to develop in men, such as facial hair, a deeper voice, and more muscle mass and bone density.

3. Regulating Sex Drive: Both men and women need testosterone to keep their sexual drive (libido) in check. It makes more nitric oxide, which widens the blood vessels in the genitals and speeds up the flow of blood.

4. Regulating Mood and Behaviour: By interacting with neurotransmitters in the brain, testosterone can change mood and behaviour. It has been shown to improve mood, energy, and the way your brain works.

5. Maintaining Bone Health: Testosterone helps keep bones healthy by making bones grow and stopping bones from breaking down. It also helps protect against bone diseases like osteoporosis.

e) Progesterone

Ans) Progesterone is a steroid hormone that is made by the ovaries, the placenta, and the adrenal glands. It is a very important part of a woman's reproductive system. Here are the main functions of progesterone: 

1. Regulating the Menstrual Cycle: Progesterone helps control the menstrual cycle by getting the uterus ready for a fertilised egg to be put there. After ovulation, progesterone causes the lining of the uterus to grow. This makes the uterus ready for a possible pregnancy.

2. Supporting Pregnancy: Progesterone is very important for keeping a pregnancy healthy. During pregnancy, progesterone causes the uterus to make more blood vessels, which feed the growing baby. Progesterone also lowers the immune system of the mother, which keeps the body from rejecting the foetus.

3. Regulating Bone Health: Progesterone helps keep bones healthy by making them grow and preventing them from breaking down. Progesterone also protects against bone diseases like osteoporosis and other bone problems.

4. Regulating Mood and Behaviour: Neurotransmitters in the brain work with progesterone to change mood and behaviour. Progesterone has been shown to make people feel calmer and less anxious, and it may also improve memory and brain function.

Part-B

Q6) Explain the role of fate maps and patterns of development. (10)

Ans) In embryology, fate maps and patterns of development are used to learn how embryos grow and change into different tissues and organs. A "fate map" is a picture that shows how the cells in an embryo will grow and change, while "patterns of development" show how the cells change and grow into different structures.

Scientists follow the path of cells in an embryo as they grow and change into different tissues and organs to make a fate map. These maps can tell us important things about how different cell populations develop and grow, as well as about the signalling pathways and genetic programmes that control how cells decide what to do. Patterns of development show how cells change into different types of cells and form different parts of the body. These processes include cell division, migration, and differentiation, as well as the formation of cell-cell interactions and signalling pathways that control the formation of different tissues and organs.

The process of gastrulation, in which an embryo's three germ layers form, is an example of a pattern of development. During gastrulation, cells on the outside of the embryo move inward and form a structure called the blastopore. This part of the body grows into the gut and other organs.

Another example of a pattern of development is the formation of the neural tube, from which the brain and spinal cord grow. In the early stages of development, cells on the dorsal side of the embryo change into neural tissue. Then, this tissue folds back on itself to make a tube. This process is controlled by a complicated mix of signalling pathways and genetic programmes that tell neural cells how to change and where to move.

The use of fate maps and patterns of development are two essential methods for acquiring knowledge regarding the growth and development of embryos, as well as the formation of various organs and tissues. Researchers can learn more about how complicated signalling pathways and genetic programmes influence development if they can determine where cells come from and how they change and form structures. This can be accomplished by determining where cells come from and how they change and form structures.

These technologies are essential for the fields of tissue engineering and regenerative medicine, as well as the study of developmental diseases and the development of treatments for those disorders. By analysing the "fate maps" and developmental patterns of various cell populations, researchers can find out how to exert control over the differentiation of individual cells and the formation of tissues. This could lead to the discovery of new treatments for a wide variety of diseases and disorders.

Q7i) How would you define a ligand in cell-to cell signalling? (3)

Ans) A ligand is a molecule that binds to a specific receptor on the surface of a target cell. This is how cells talk to each other. This starts a chain of signals that tells the target cell what to do. Ligands can be proteins, peptides, hormones, neurotransmitters, or other small molecules that cells secrete and that bind to receptors on neighbouring cells.

Ligand-receptor interactions are important for many body functions, such as neurotransmission, hormone signalling, immune response, cell growth and differentiation, and the transmission of nerve impulses.

Once a ligand binds to its receptor, it can activate several signalling pathways, such as second messenger systems, G-protein coupled receptors, and receptor tyrosine kinases. These pathways can change how enzymes work, how genes are expressed, and how cells react in other ways.

Ligands are an important part of cell-to-cell signalling because they send information between cells and control how the body works. Understanding how ligands and receptors work together is important for making therapies that target specific receptors and signalling pathways and for figuring out the causes and treatments of diseases and disorders that involve abnormal cell signalling.

Q7ii) What is the difference between Juxtacrine and paracrine signalling? (3)

Ans) With both Juxtacrine and paracrine signalling, information is sent from one cell to another. Juxtacrine signalling happens when a signalling molecule on one cell talks to a receptor on an adjacent cell. Most of the time, this happens when two cells touch each other directly. During Juxtacrine signalling, the message is sent across the cell membrane, and the cell that responds must be close to the cell that sent the message. During development, Juxtacrine signalling is often involved in things like cell differentiation and how tissues are laid out.

Paracrine signalling, on the other hand, happens when a signalling molecule is released by one cell and acts on nearby cells. In paracrine signalling, the signalling molecule moves through the space outside the cell and binds to receptors on nearby cells. This makes it possible to send signals to more places, and it can lead to the coordinated control of physiological processes in more than one cell or tissue.

The distance over which the signal is sent is a key difference between Juxtacrine and paracrine signalling. Juxtacrine signalling happens when two cells are right next to each other, while paracrine signalling can happen at a greater distance.

Q7iii) How is EMT used in the embryo and in the adult? (4)

Ans) EMT, which stands for "epithelial-mesenchymal transition," is a process in which epithelial cells change into mesenchymal cells. This can happen during embryonic development and in some adult tissues. This process is important because it affects how tissues change, how cells move, and how cells change into different types.

EMT is a very important part of how organs and tissues grow and form in an embryo. For instance, during gastrulation, EMT lets cells from the primitive streak move and change into mesodermal and endodermal tissues. EMT lets neural crest cells move to different parts of the developing embryo and change into different types of cells, like sensory neurons, melanocytes, cartilage, and bone cells.

EMT is involved in the healing of wounds, the repair and growth of adult tissues, and the spread of cancer. For example, when a wound is healing, EMT can help the epithelial cells at the edge of the wound move and multiply. This makes new tissue form. EMT can make cancer cells more aggressive and able to spread to other parts of the body as the cancer gets worse. This lets them get into other parts of the body.

Q8i) Chose the correct answer form alternatives provided. (5)

a) Fertilization is responsible for the activation/arrest of development.

Ans) Fertilization is responsible for the activation of development.

b) Activation of the sperm ensures/does not ensure that sperm will meet the egg.

Ans) Activation of the sperm does not ensure that sperm will meet the egg.

c) In organisms with external/internal fertilization, chemotactic mechanisms have been evolved to attract the sperm towards the egg.

Ans) In organisms with external fertilization, chemotactic mechanisms have been evolved to attract the sperm towards the egg.

d) A period of maturation in the female reproductive tract required for the transformation of sperm is known as activation/capacitation.

Ans) A period of maturation in the female reproductive tract required for the transformation of sperm is known as capacitation.

e) Sperm using an enzyme called acrosin/hyaluronidase penetrate their way through zona pellucida.

Ans) Sperm using an enzyme called acrosin penetrate their way through zona pellucida.

Q8ii) Fill in the blanks with suitable words.                                                                              (5)

a) ………………. is the extension of egg cytoplasm around the entering sperm head.

Ans) Fertilization cone is an extension of the egg cytoplasm which is around the head of the entering sperm.

b) Inhibitor of microfilament formation such as ……………… prevents the formation of fertilization cone.

Ans) Inhibitor of microfilament formation such as cytochalasin B prevents the formation of fertilization cone.

c) The early response for the entry of sperm into the egg is prevention of ………………. .

Ans) The early response for the entry of sperm into the egg is prevention of polyspermy.

d) The ………………. for polyspermy is mediated by the electrical depolarization of egg plasma membrane.

Ans) The fast block for polyspermy is mediated by the electrical depolarization of the egg plasma membrane.

e) The slow block to polyspermy is achieved by …………… reaction.

Ans) The slow block to polyspermy is achieved by the cortical reaction.

Q9a) Describe the process of internalization of mesoderm in frog. What are the end results of the gastrulation process? (5)

Ans) Gastrulation is a complicated process in frogs that involves the layer of mesoderm moving inside the body. The blastopore lip is home to a special group of cells called "bottle cells," which oversee this process.

During gastrulation, the lip of the blastopore starts to invaginate, or fold inward, making what is called the dorsal lip of the blastopore. The bottle cells then move through the blastopore and into the interior of the embryo, where they cause the cells above them to become internalised and form the mesodermal layer. The mesoderm is made by convergent extension movements, which make the cells get narrower and longer, and cell division, which causes the mesodermal layer to get bigger.

Frogs move their mesoderm inside their bodies for several important reasons. First, it helps set up the embryo's basic body plan by laying the groundwork for the notochord to grow. The notochord is a very important part of the embryo's dorsal-ventral axis, which is the direction of the embryo's back. Second, the mesoderm gives rise to many important tissues and organs, such as the muscles, bones, blood vessels, kidneys, and reproductive organs. Lastly, when the mesoderm moves inside, it helps make a physical separation between the ectoderm and endoderm layers. This is important for the digestive and respiratory systems to develop properly.

The three germ layers, the ectoderm, mesoderm, and endoderm, are formed at the end of the gastrulation process. All the tissues and organs of the embryo come from these layers, which are set up in a certain way that is important for normal development. The skin, nervous system, and organs that sense things are all made from the ectoderm. The muscles, bones, blood vessels, kidneys, and organs that make babies are all made from the mesoderm. The lining of the digestive and respiratory systems, as well as the liver and pancreas, come from the endoderm.

In gastrulation, the basic body plan of the embryo is also set up. This is in addition to the formation of the germ layers. This includes the formation of the notochord, which defines the embryo's dorsal-ventral axis, and the setting up of the left-right axis, which is important for the heart and other organs to be in the right place.

Q9b) Discuss the process of development of extra embryonic membranes in chick. (5)

Ans) Gastrulation is a complicated process in frogs that involves the layer of mesoderm moving inside the body. The blastopore lip is home to a special group of cells called "bottle cells," which oversee this process.

During gastrulation, the lip of the blastopore starts to invaginate, or fold inward, making what is called the dorsal lip of the blastopore. The bottle cells then move through the blastopore and into the interior of the embryo, where they cause the cells above them to become internalised and form the mesodermal layer. The mesoderm is made by convergent extension movements, which make the cells get narrower and longer, and cell division, which causes the mesodermal layer to get bigger.

Frogs move their mesoderm inside their bodies for several important reasons. First, it helps set up the embryo's basic body plan by laying the groundwork for the notochord to grow. The notochord is a very important part of the embryo's dorsal-ventral axis, which is the direction of the embryo's back. Second, the mesoderm gives rise to many important tissues and organs, such as the muscles, bones, blood vessels, kidneys, and reproductive organs. Lastly, when the mesoderm moves inside, it helps make a physical separation between the ectoderm and endoderm layers. This is important for the digestive and respiratory systems to develop properly.

The three germ layers, the ectoderm, mesoderm, and endoderm, are formed at the end of the gastrulation process. All the tissues and organs of the embryo come from these layers, which are set up in a certain way that is important for normal development. The skin, nervous system, and organs that sense things are all made from the ectoderm. The muscles, bones, blood vessels, kidneys, and organs that make babies are all made from the mesoderm. The lining of the digestive and respiratory systems, as well as the liver and pancreas, come from the endoderm.

In gastrulation, the basic body plan of the embryo is also set up. This is in addition to the formation of the germ layers. This includes the formation of the notochord, which defines the embryo's dorsal-ventral axis, and the setting up of the left-right axis, which is important for the heart and other organs to be in the right place.

Q10a) Choose the correct term: (5)

i) The morula/blastocyst implants in the uterine endometrium.

Ans) The blastocyst implants in the uterine endometrium.

ii) The ICM/trophoblast gives rise to the embryo.

Ans) The inner cell mass (ICM) gives rise to the embryo.

iii) Ectopic pregnancy is the result of implantation inside/outside the uterus.

Ans) Ectopic pregnancy is the result of implantation outside the uterus.

iv) HCG maintains/degenerates the corpus luteum.

Ans) HCG (Human chorionic gonadotropin) maintains the corpus luteum.

v) Uteroplacental circulation occurs due to development of blood-filled space in syncytiotrophoblast/inner cellular layer of trophoblast.

Ans) Uteroplacental circulation occurs due to the development of blood-filled spaces in the syncytiotrophoblast.

Q10b) How do genetic and environmental defects cause problems in development? (5)

Ans) Developmental problems can be caused by several things, such as genes and the environment. Mutations or problems with the way chromosomes are put together can change the way genes that are needed for normal development are expressed. This can lead to genetic defects. Environmental defects can happen when a person is exposed to toxins, drugs, infections, or other things in the environment that can stop normal growth. In both cases, the resulting defects can be very bad for the health and well-being of the person.

Genetic defects can be passed down from one or both parents, or they can happen on their own because of mistakes made when copying DNA or dividing cells. Down syndrome, cystic fibrosis, and sickle cell anaemia are all examples of genetic problems that can cause problems with development. These conditions can affect many different body systems and can cause a wide range of physical, mental, and behavioural symptoms.

Toxins like alcohol, tobacco, and drugs can cause birth defects if they are taken in while a woman is pregnant. These substances can stop normal development and lead to a few birth defects, such as foetal vsyndrome, low birth weight, and birth before the baby is ready. Serious birth defects can also be caused by infections like rubella, cytomegalovirus, and the Zika virus.

Both genetic and environmental defects can affect development in different ways, depending on how bad they are and when they happen. For instance, mistakes that happen early in the development process can have worse effects than those that happen later. Also, problems with the expression of important genes or proteins can have worse effects than problems with non-important genes.

The normal order of gene expression can be messed up by genetic defects, which is one way they can cause problems during development. Genes are turned on and off in a certain order and pattern during development. This is important for the formation of organs, tissues, and other structures. When genes are changed or broken, it can change when and how genes are expressed. This can lead to abnormal development.

Environmental issues can disrupt cell division, differentiation, and motility, halting development. Lead can inhibit cells from dividing and cause birth abnormalities like low birth weight and brain damage. Infections can potentially impede development by targeting cells or organs, disrupting signalling pathways, and affecting gene expression.

Genes and the environment can alter a person's behaviour and health. Down syndrome children may take longer to communicate and think, and drinking alcohol during pregnancy might induce hyperactivity and impulsivity.