Biology Test-8

Bile juice, Pancreatic juice secreted by the organs plays an important role in the digestion of fats. Bile juice is secreted by the liver.

• It does not contain any types of enzymes.
• The bile juice helps to make the food alkaline and break down the fat molecules.

Pancreatic juice is secreted by the pancreas.

• It contains enzymes like amylase, trypsin, pancreatic lipase, nucleases, amylase, and lipase.
• Secretion of the Pancreatic juice is regulated by the hormones secretin and cholecystokinin.

Lipase is the digestive enzyme of fat.

Ptyalin is the digestive enzyme of the Saliva.

Hydrochloric acid is produced naturally in the human stomach to help the digestion of food.

Cleistogamy is a condition where flowers do not open. In such flowers, the anther and stigma is close in such a way that when anther dehisce in the flower buds, pollen grains comes in contact with stigma to effect pollination. The offspring produced have limited genetic diversity.

Advantages of Cleistogamy:

i. Ensure seed formation in the absence of any pollinating agents.

ii. Commercially cost effective.

Protoplasm:

• It is the living part of the cell, which comprises different cellular organelles. It is a jelly-like, colorless, transparent, and viscous living substance present within the cell wall. The term protoplasm was proposed in the year 1835 and is known as the primary substance, as it is responsible for various living processes. It was believed that cells were containers of protoplasm. However, the concept could not explain the origin of structures formed within the cell, primarily the nucleus.
• The cytoplasm is the initial component of protoplasm, which is found between the cell membrane and the cell nucleus in a eukaryotic cell. In the cell, a cytoplasm plays a vital role in maintaining the cell environment, maintaining the shape of cells, and also stores substances required by the organelle.
• The nucleus is the second component of the protoplasm, which stores the genetic information of an organism.
• Ribosomes are also found in the nucleus, which is essential for the production of proteins in the cell.
• Prokaryotes contain a nucleoid instead of a nucleus where all the genetic information is found.
• Proteins, fats, enzymes, hormones, all make up the protoplasm. These are either dissolved or suspended in the water component of the protoplasm.

F.W. Went cuts off the tip of oat coleoptiles and placed it on small agar blocks and allowed the chemical influence to diffuse in the agar. From there, he isolated auxin in the agar. Then he placed these agar blocks on the side on one side of freshly decapitated coleoptiles. He then observed that the coleoptile grew and bent away from the side on which the block was placed. The degree of curvature of coleoptile was found to be directly proportional to the concentration of chemical influence in the agar box, which he named auxin, responsible for the phototropic response.

During Aerobic Respiration, ATP synthesis occurs in mitochondria.

The breaking of the C-C bonds of complex compounds through oxidation within the cells, leading to the release of a considerable amount of energy is called respiration.  The compounds that are oxidized during this process are known as respiratory substrates. Along with the energy carbon dioxide and metabolic water is also released as a by-product in respiration.

$C_6{H}_{12}{O}_6+6O_2\to 6C{O}_2+6H_{2}O+Energy$

Respiration is of two types:

1. Aerobic Respiration: It occurs in the presence of oxygen. Here the food is completely oxidized into CO2.  More ATPs are produced here (38 ATP). It occurs in the mitochondria
2. Anaerobic respiration: It occurs in the absence of oxygen. Here the food is partially oxidized into alcohol & organic acids. It is generally observed in bacterias and human muscle cells. Only 2 ATPs are produced in this process

Steps of Aerobic respiration:

1. Glycolysis - Occurs in Cytosplasm/ Cytosol
2. Formation of Acetyl COA/ Link reaction - Occurs in the mitochondrial matrix
3. TCA cycle or Krebs cycle - occurs in the matrix of mitochondria
4. Electron Transport System (ETS) - Occurs in cristae or inner mitochondrial membrane of mitochondria

During the ETS ATP is synthesized in the inner mitochondrial membrane by the action of the enzyme ''ATP synthase''

So, it is clear that ATP synthesis occurs in mitochondria. For this reason, only mitochondria are also called the powerhouse of the cell.

Tapeworm in the host's stomach is NOT an example of a one-sided symbiotic relationship (Commensalism). A tapeworm in the host's stomach is an example of Parasitism.

Symbiosis is a close relationship between two species in which at least one species benefits. For the other species, the relationship may be positive, negative, or neutral. There are three different types of symbiotic relationships:

• Mutualism
• Commensalism(one-sided symbiotic relationship)
• Parasitism

Mutualism: It is a type of symbiotic relationship in which both species benefit. Example: goby fish and shrimp.

Commensalism: It is a type of symbiotic relationship in which one species benefits while the other species are not affected. Example: mites attach themselves to larger flying insects to get a “free ride”.

Parasitism: It is a type of symbiotic relationship in which one species (the parasite) benefits while the other species (the host) is harmed. Example: Roundworms are parasites of mammals, including humans, cats, and dogs.

Community ecology or synecology is the study of the interactions between species in communities on many spatial and temporal scales, including the distribution, structure, abundance, demography, and interactions between coexisting populations. Therefore, if the geographical area is the same they belong to a community.

New species originate as a result of large, discontinues variations which appears suddenly, was according to mutation theory.

The feature of mutation theory are:

i. It may occur in any direction

ii. It arise from the time to time amongst the individual of a naturally breeding population

iii. It is heritable and established new forms of species.

iv. Mutation are large, discontinues variations which appears suddenly, which is different from fluctuating variation of Darwin’s, which is small and directional.

Scars on the seed coat through which developing seeds are attached to the fruit is called as Hilum. Above the Hilum, there is a small pore called micropyle.

Protective covering of seed called as seed coat. Seed coats has two layer testa and inner is called as tegmen.

Embryo consist of embryonal axis and two cotyledons. At the two end of the embryonical axis are present radical (hypocotyl) and plumule (epicotyl).

Anther is a terminal bilobed structure and the wall of anther consist of following layers:

● Endothecium: The cell of endothecium layer have α-cellulosic fibrous bands arising from the inner tangential wall which help in dehiscence of anther due to hygroscopic nature. They are absent in hydrophytes.

● Epidermis: It is the outermost ,singled layered and protective function . The epidermis of Arceuthobium (parasite an develops some fibrous thickenings and called as exothecium).

● Middle layer:Cell of this layer are ephemeral and are 1 to 3 layered, which degenerate at maturity.

● Tapetum: It is the innermost layer of anther wall which surrounds the sporogenous tissue . Tt nourishes the developing pollen grains .Cell of this layer possess dense cytoplasm and generally have more than 1 nucleus and show increase in DNA content.

Fermentation is a kind of anaerobic respiration, carried out by fungi and bacteria.

It is of 2 types:

A. Alcoholic fermentation

B. Lactic acid fermentation

The major difference: Alcoholic fermentation result in release of CO₂ along with ethanol while lactic acid fermentation release lactic acid only.

Australopithecus, (first Apeman): The early human stock gave rise to Australopithecus. It is the connecting link between apes and man.

Characteristics:

i. They were 1.5 m high and had human as well as ape characters.

ii. They had bipedal locomotion, an omnivorous diet, and had erect posture.

iii. Brain capacity 500cc, similar to that of an ape.

iv. They had a lumbar curve in the vertebral column and the pelvis was broad.

Milk Ietdown hormone is Oxytocin.

Milk letdown means theejection of a mother's milk from the alveoli of the breast into the mammary ducts and to the nipple. When the nipple is sucked theProlactinacts on the milk-making tissues. TheOxytocin hormonecauses the breast to push out or 'let down' the milk.

• Prolactin is a hormone produced by thepituitary gland which sits at the bottom of the brain. It causes breasts to grow and develop and causes milk to be made after a baby is born.
• Oestrogen is the primary female sex hormone. It is responsible for the development and regulation of the female reproductive system and secondary sex characteristics.
• Progesterone prepares the endometrium for the potential of pregnancy after ovulation. It triggers the lining to thicken to accept a fertilized egg.

The activity of cambium ring is not uniform throughout the entire year but marked affected by variation in external environment, i.e. climate as well an internal environment of the plants. The secondary xylem or the wood produced in different season with the differential activity of cambium. 

Characteristics of Spring wood: In the spring season, cambium is very active and produce large number of xylary elements. The vessel are produced with the wider lumens as more water is needed to meet the requirements by increasing transpiring surface in spring seasons. The wood so formed is called as spring wood or early wood. The spring wood is lighter in colour and has lower density. 

Characteristics of Autumn wood: In winter, the cambium is less active and as result, fewer xylary elements are formed and vessels have narrow lumen as the less water is needed. the wood formed during this season is called as Autumn wood or late wood. This wood is darker in color and has higher density.

The male reproductive system includes a pair of testes along with accessory ducts, glands, and the external genitalia. Each testis has about 250 compartments called testicular lobules. Each lobule contains one to three highly coiled seminiferous tubules in which sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells. The male germ cells undergo meiotic divisions finally leading to sperm formation, while Sertoli cells provide nutrition to the germ cells. The regions outside the seminiferous tubules called interstitial spaces contain small blood vessels and interstitial cells or Leydig cells. 

Leydig cells synthesise and secrete testicular hormones called androgens.