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The correct answer is Free-central.

Concept:

• The arrangement of ovules within the ovary is known as placentation.
• The placenta is a tissue, which develops along the inner wall of the ovary.
• The ovule or ovules remain attached to the placenta.

Explanation:

• The gynoecium in the Caryophyllaceae family are syncarpous, i.e., the carpels are fused together.
• However, the styles and stigma remain free from carpel.
• In Caryophyllaceae family ovary is unilocular (only one locule).
• The unilocular ovary shows the Free-central type of placentation.
• Free-central placentation: When the ovules are borne on central axis and septa are absent, the placentation is called free-central.

Thus, In family Caryophyllaceae, placentation is Free-central.

Additional Information

• Parietal placentation:
• It is found in the Brassicaceae family.
• In this type of placentation, the ovules develop on the inner wall of the ovary or on peripheral part.
• Basal placentation:
• ​It is found in the Asteraceae family.
• In this type, the placenta develops at the base of the ovary and a single ovule is attached to it.
• Axile placentation:
• ​It is found in the Solanaceae (potato) family.
• In this type, the placenta is axile and the ovules are attached to it in a multilocular ovary.

The hind wings of houseflies are modified into little halteres. During the flight, these beat faster than fore wings.

Key Points

• The common name of a housefly is Musca domestica.
• It belongs to the order Diptera and genus Musca.
• About 90 percent of all flies occurring in human habitations are houseflies.
• The adult housefly is dull grey with dirty-yellowish areas on the abdomen and longitudinal lines on the thorax.
• Shortened hindwings are called halteres. They are modified hindwings.
• They are present in pairs just at the back of the forewings.
• Halteres are used in balance to help stabilize the housefly in flight.
• Houseflies flap their halters at high speeds during flight.
• If one haltere is removed, the housefly can only fly in circles.
• If both halteres are removed, the fly cannot take flight at all.

Additional Information

• Kingdom Animalia is divided into sub-groups which is known as Phylum. There are 11 phyla in the kingdom Animalia:
• Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata.
• Arthropoda is the largest phylum of Animalia.
• Arthropoda includes insects.

The correct answer is Petrifaction.

Concept:

• Fossilization is defined as the physical, chemical and biological processes that lead to the preservation of plant and animal remains over time.
• Some common methods of fossilization are petrifaction, permineralization, compression, casts and molds.

Key Points

• Petrifaction is the process by which biological material transforms into a fossil by replacing the original material and filling the original pore spaces with minerals.
• The fossils formed as a result of this process typically contain a significant amount of the original material of the specimen.
• Groundwater containing dissolved minerals fills the pore spaces and cavities of specimens, most notably bone, shell, or wood.
• When these minerals precipitate out of the water, they fill the pores of the organisms tissues.
• These are the best, but most rare, types of fossils because they preserve both the external forms and the internal structures.
• The cellular details are preserved due to the infiltration of minerals like MgCO₃, CaCO₃, SiO₂, FeS, etc. into the tissue.

Additional Information

• Pseudofossils: 
• Inorganic rocks that appear to be fossils are sometimes mineral deposition.
• Compression:
• Plant parts such as leaves, stems, and seeds are compressed by the sediments' vertical pressure.
• Flattened plant parts are retained as thin carbonaceous films and the outline of external features.
• Internal structures are generally not preserved.
• Incrustation:
• The deposition of carbonate minerals and iron occurs in the form of a hard cast or incrustation around the plant parts.

The correct answer is Excretory.

Key Points

• Unio is a genus of medium-sized freshwater mussels, aquatic bivalve mollusks (Phylum Mollusca) in the family Unionidae, the River mussels.
• Unio is the type genus of the family Unionidae.

Keber's organ

• It is the excretory organ in certain organisms like molluscs (which includes - Mussels, snail, octopus, clams etc.).
• It is otherwise also called as 'pericardial gland'.
• Keber's organ function is similar to that of the kidney and are present in addition to the kidneys (organ of Bojanus).
• Structure:
• ​It is a large, reddish-brown glandular mass.
• Location:
• It may be over the auricle surface (articular glands), on the pericardium (pericardial glands), or in both positions. i.e., situated antero-lateral to the pericardium into which it discharges the waste material.
• They are collected from that point by the kidney.
• Function:
• The organ is responsible for the removal of nitrogenous wastes.
• The wastes are excreted into pericardium from where these are collected by the 'organ of Bojanus' to be discharged outside the body.
• Pericardial glands of bivalves have revealed that these consist of podocytes where the base of cytoplasmic extensions gives rise to numerous pedicels.
• These form a net with slits through which the fluid is filtered.

Additional Information

Unio: Organs and their function

• Excretory organ: The excretory system of Unio includes a pair of kidneys (organs of Bojanus), a pericardial gland (Keber's organ).
• Vascular: The blood vascular system is well developed and is of open type. It comprises the blood, heart, pericardium, arteries, sinuses, and veins.
• Digestive: The liver is the only digestive gland that surrounds the stomach. It secretes digestive enzymes and its cells are capable of ingesting food particles where intracellular digestion (i.e. digestion occurs in a cell) also occurs.
• Reproductive: In Unio, the sexes are separate (dioecious) but there is no sexual dimorphism.

About Phylum Mollusca

• Mollusks are terrestrial or aquatic (marine or freshwater) animals having a calcareous shell.
• The body is covered by a calcareous shell and is un-segmented with a distinct head, muscular foot, and visceral hump.
• A soft and spongy layer of skin forms a mantle over the visceral hump.

Unio (Fresh-water Mussels)

• It belongs to bivalve molluscs.
• The animal is sedentary and eventually settles down on the bottom of the river or the lake through the mud or sand.

Concept-

• The parasympathetic nervous system is composed mainly of the cranial and spinal nerves.
• The preganglionic neurons, arising from either the brain or sacral spinal cord, synapse(meet) with just a few postganglionic neurons which are located in or near the effector organ (muscle or gland).
• The parasympathetic nervous system is responsible for the body's rest and digestion response when the body is relaxed, resting, or feeding.

Key PointsNerves of the parasympathetic nervous system-

• Nerve fibres of the PSNS arise within the central nervous system. The primary nerves involved are cranial nerves. Below are some of the main cranial nerves in the PSNS:
• Vagus nerve – approximately 75% of all the parasympathetic nerves are vagus nerves. These nerves have branches in many key organs such as the stomach, kidneys, bladder, and reproductive organs.
• Oculomotor nerve – these nerves are able to help constrict the pupils.
• Glossopharyngeal nerve – these nerves project to the salivary glands to provide extra salivation to the tongue

Functions of parasympathetic nervous system-

• Parasympathetic nervous system is able to decrease heart rate, especially when at rest after completing physical exercise or after stressful situations.
• It also stimulates salivation of the mouth to enable the easier digestion of food through the enzymes within saliva.
• Digestion is also promoted within the stomach as well as releasing bile for the body to digest fats.
• The PSNS also contracts the bladder so that urination can occur, in addition to being able to move food within the intestines down the digestive tract to enable bowel movements which is called peristalsis.
• When stressed, the PSNS triggers the necessary responses in order to return to homeostasis (the maintaining of balancing internal physiology).
• Without the PSNS, we may either constantly be in a state of elevated stress response or the regulation of our everyday bodily processes would be dysfunctional, such as being unable to digest food or control our bladder.

Additional Information

• The sympathetic nervous system can:
• accelerate heart rate,
• widen bronchial passages,
• decrease motility of the large intestine,
• constrict blood vessels,
• increase peristalsis in the esophagus,
• cause pupillary dilation,
• piloerection (goose bumps),
• perspiration (sweating),
• raise blood pressure.

Concept-

• Kingdom Plantae is divided into five groups- Algae, Bryophyta, Pteridophyta, Gymnosperm, and Angiosperm.
• Algae
• The plant body is not differentiated from roots, stems, and leaves.
• They are also known as thallophyta.
• Bryophyta
• These are small terrestrial plants.
• They show differentiation in the body design, with stem, leaf-like structures, and root-like structures.
• Pteridophyta
• The plant body is differentiated into roots, stems, and leaves, apart from having a specialized tissue for conduction.
• Gymnosperms
• Gymnosperms are plants with naked seeds.
• Angiosperms
• Angiosperms are seed-bearing plants. Seeds develop inside tissues that get modified to form the fruit of the plant.

Explanation-

• Evolutionarily, Pteridophyta is the first terrestrial plant to possess vascular tissues – xylem and phloem.
• Bryophytes lack vascular tissues.
• They produce a multicellular body called a sporophyte.
• The sporophyte is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it.
• Some cells of the sporophyte undergo reduction division (meiosis) to produce haploid spores.
• All the multicellular eukaryotic plants are autotrophic i.e., they manufacture their food by photosynthesis.
• Oogamous type of sexual reproduction is found in bryophytes.
• As a result of the fertilization, a diploid zygote is formed.
• The zygote does not undergo reduction (meiosis) immediately, but initiates the sporophytic generation.
• Sporophytic generation is a diploid stage.

Therefore, "zygote undergoes meiosis" is the false statement about bryophytes.

The correct answer is Both.

Concept:

• G.H. Hardy and Wilhelm Weinberg independently described the basic principle of population genetics that is known as the Hardy-Weinberg principle.
• Hardy-Weinberg principle states that gene frequency in a population remains stable and constant from generation to generation.
• The gene pool is constant and this is called Hardy-Weinberg equilibrium or genetic equilibrium.
• Gene pool - total number of genes and their alleles in a population.
• It can be expressed by a mathematical equation:

​p² + 2pq + q² = 1

where p and q are frequencies of the dominant and recessive allele respectively.

• This equation can also be used to calculate the genotypic frequencies in a population at equilibrium.
• ​p² - homozygous dominant frequency
• q² - homozygous recessive frequency
• 2pq - heterozygous frequency

Explanation:

• Hardy-Weinberg equilibrium is affected by Mutation, Natural selection, Genetic drift, Genetic recombination and Gene migration or gene flow.

1. Mutation-

• Advantageous mutations lead to new phenotypes and over few generations, result in speciation.

2. Natural selection-

• It is a process in which heritable variations enhance resource utilization for few individuals, enabling them to survive and reproduce better.
• This leads to a change in the characteristics of the population, giving rise to new forms.
• Natural selection can have the following three effects:

1. Stabilizing: Large number of individuals acquire mean character value so peak gets higher and narrower.
2. Directional: Large number of individuals acquire value other than mean character value so peak shifts in one direction.
3. Disruptive: Large number of individuals acquire peripheral character values at both ends of the distribution curve and hence two peaks are formed.

Explanation-

• Auxins refer to a group of plant growth hormones or regulator (PGR).
• Auxin (from Greek ‘auxein’ : to grow) was first isolated from human urine.
• The term ‘auxin’ is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic compounds having certain growth-regulating properties.
• Seedless fruits are called parthenocarpic fruit which can be produced by a spray of auxin(IAA).

Therefore statement 1 is CORRECT.

• Fruits are the results of fertilization, there are a few species in which fruits develop without fertilization. Such fruits are called parthenocarpic fruits.
• Such fruits are seedless.

Therefore statement 2 is CORRECT.

• Gibberellins are another kind of promoter PGR.
• There are more than 100 gibberellins reported from widely different organisms such as fungi and higher plants.
• They are denoted as GA1, GA2, GA3, and so on.
• Gibberellins, Auxin, etc. are effective in producing parthenocarpic fruit.

Therefore statement 3 is INCORRECT.

• Fruits are the results of fertilization, there are a few species in which fruits develop without fertilization. Such fruits are called parthenocarpic fruits.

Therefore statement 4 is CORRECT.

Concept-

• Lichen is the symbiotic association of fungi and algae.
• The algal component is known as photobiont.
• The fungal component is known as mycobiont.
• The photobiont prepare food for fungi i.e. algae are autotrophic.
• The fungal component or mycobiont is involved in:
• Outer covering for protection.
• Attachment to substratum
• Protection against harmful radiations.
• The fungi provide shelter and absorb mineral nutrients and water for their partner i.e. fungi are heterotrophic.
• Reproduction in lichens can be asexual as well as sexual reproduction.
• Lichens are found in habitats like walls, window panes, barren rocks, cooled volcanic larva, tree bark and soil.
• Some examples of lichen are: Parmelia, Cladonia, Cetraria, etc.

Explanation-

• Lichen is an air pollution indicator.
• Lichens are very sensitive to sulfur dioxide.
• And it dies in high levels of sulfur dioxide.
• So lichens are not found in the atmosphere which is polluted.

Therefore lichens are a good indicator of air pollution.

Concept-

• A dental formula is a system for summarizing the number of each type of tooth (incisor, canine, premolar, molar) in each quadrant of the mouth.
• Dental formulae vary between species and may be different for the maxillary and mandibular dentition.

Key Points

• Rabbit teeth are also elodont, meaning that they continually grow throughout the life of the rabbit.
• It has no canines in jaw.
• There is a gap in both the jaws at the location of canines. It is called as diastema.
• The dental formula of the rabbit is as follows: 2( I= 2/1, C=0/0, PM=3/2, M=3/3 ) = 28, where I=incisors, C=canine, P=premolar, M=molar.
• 2 main incisors top and bottom, 2 tiny incisors behind the main top ones, and 22 premolars and molars- each side has 6 on the top and 5 on the bottom.
• The part of the teeth visible from above the gum line is called the clinical crown, while the portion below the surface is the reserve crown.
• The upper incisor has hard enamel on the rostral surface and soft dentin on the lingual surface.
• There is an interesting arrangement of the upper incisor in that the second incisor is behind the first incisor.
• The second incisor is also called the peg tooth.
• At rest, the opposing incisors, premolars, and molars remain in contact.
• While eating, rabbits use the incisors to cut the food using a vertical, chopping motion. Once the food is passed to the cheek teeth (premolars and molars), a rotating horizontal stroke is used to grind the food.

Additional Information The dental formulae of some common mammals are given below:

a) Man & Monkey    \(I \frac{2}{2}, C \frac{1}{1}, Pm \frac{2}{2}, M \frac{3}{3}= \frac{2123}{2123}\times 2=32\)

b) Rabbit                 \(I \frac{2}{1}, C \frac{0}{0}, Pm \frac{3}{2}, M \frac{3}{3}= \frac{2033}{1023}\times 2=28\)

c) Cow & Goat        \(I \frac{0}{3}, C \frac{0}{1}, Pm \frac{3}{3}, M \frac{3}{3}= \frac{0033}{3133}\times 2=32\)

d) Dog                    \(I \frac{3}{3}, C \frac{1}{1}, Pm \frac{4}{4}, M \frac{3}{2}= \frac{3142}{3143}\times 2=42\)

e) Rat & Mouse      \(I \frac{1}{1}, C \frac{0}{0}, Pm \frac{0}{0}, M \frac{3}{3}= \frac{1003}{1003}\times 2=16\)

f) Elephant             \(I \frac{1}{0}, C \frac{0}{0}, Pm \frac{3}{3}, M \frac{3}{3}= \frac{1033}{0033}\times 2=26\)

g) Kangaroo          \(I \frac{3}{2}, C \frac{1}{0}, Pm \frac{2}{2}, M \frac{4}{4}= \frac{3124}{3124}\times 2=34\)

h) Sheep               \(I \frac{0}{3}, C \frac{0}{1}, Pm \frac{3}{3}, M \frac{3}{3}= \frac{0033}{3133}\times 2=32\)