Biology Mock Test- 4 - Class 10 MCQ

Only those variation which are useful and have advantage get selected.

Explanation:

• Feathers in dinosaurs and birds: Some dinosaurs had feathers, although they could not fly. Birds also have feathers that help them to fly.


• Evolutionary connection: The presence of feathers in both dinosaurs and birds indicates an evolutionary connection between the two groups.


• Evolutionary theory: According to the theory of evolution, birds have evolved from reptiles.


• Homologous structures: Feathers are considered homologous structures in both dinosaurs and birds, indicating a common evolutionary origin.


• Adaptation: Feathers likely evolved in dinosaurs for reasons other than flight, such as insulation or display, and were later adapted for flight in birds.

By analyzing the presence of feathers in both dinosaurs and birds, scientists can better understand the evolutionary history of these organisms and how certain traits have been passed down and modified over time.

Neuromuscular junctions are between axon ending and muscles and junction between axon ending of one neuron and dendrites of another neuron is termed synapse.

Abscisic acid induces the formation of abscission  zone in the leaf stalk or petiole and brings about shedding of leaves. Thus, it is not associated with the growth of the plant. 

The pancreas is the only unpaired endocrine gland in the human body. It plays a crucial role in regulating blood sugar levels by producing insulin and glucagon. Here are some key points about the pancreas:

• It is located behind the stomach.
• The pancreas has both endocrine and exocrine functions.
• As an endocrine gland, it releases hormones directly into the bloodstream.
• Insulin lowers blood sugar, while glucagon raises it.

Other glands, like the ovaries and testes, are paired, meaning there are two of each in the human body.

This is because anaerobic respiration occurs in the absence of molecular oxygen to break down glucose into ethanol or lactic acid, carbon dioxide and energy (2 ATP)

Exchange of gases in a mammal

The exchange of gases, specifically oxygen (O₂) and carbon dioxide (CO₂), in a mammal takes place in the alveoli.

• Trachea: The trachea is responsible for conducting air to and from the lungs, but it does not participate in the exchange of gases.


• Bronchi: The bronchi are the main air passages in the lungs, but they do not directly participate in the exchange of gases.


• Bronchioles: Bronchioles are smaller branches of the bronchi that lead to the alveoli. While they play a role in directing air to the alveoli, they do not directly participate in gas exchange.


• Alveoli: The alveoli are tiny air sacs located at the end of the bronchioles. They are the primary site of gas exchange in the respiratory system. Oxygen from the inhaled air diffuses across the thin walls of the alveoli into the bloodstream, while carbon dioxide diffuses from the bloodstream into the alveoli to be exhaled.

Therefore, the correct answer is d. Alveoli, where the exchange of gases [O₂ and CO₂] takes place in a mammal.

Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and blood cells themselves.

Explanation:
The fourth trophic level is the level of top carnivores in a food chain or food web. These organisms are at the highest level of the trophic pyramid and feed on the organisms from the level below them. They are typically large predators that consume other carnivores or omnivores.
Key Points:
- The fourth trophic level consists of top carnivores.
- Top carnivores are the apex predators in a food chain or food web.
- They are typically large predators that feed on other carnivores or omnivores.
- Examples of top carnivores include lions, tigers, wolves, and sharks.
- Top carnivores have no natural predators and are at the top of the trophic pyramid.
Summary:
The fourth trophic level consists of top carnivores, which are apex predators that feed on other carnivores or omnivores. They occupy the highest level in the trophic pyramid and have no natural predators. Examples of top carnivores include lions, tigers, wolves, and sharks.

The movement of a plant subjected to constant directional pressure is called thigmotropism, from the Greek words thigma meaning “touch,” and tropism implying “direction.” Tendrils are one example of this. The meristematic region of tendrils is very touch sensitive; light touch will evoke a quick coiling response. Cells in contact with a support surface contract, whereas cells on the opposite side of the support expand. Application of jasmonic acid is sufficient to trigger tendril coiling without a mechanical stimulus.

The growth of pollen tubes towards ovules is due to chemotropism. Chemo-tropism is growth of organisms such as bacteria and plants, navigated by chemical stimuli from outside of the organism or organism's part.

Flow of energy is unidirectional:
The statement "Flow of energy is unidirectional" means that energy flows in one direction only, and it does not come back to the previous levels. Let's understand this concept in detail:
Explanation:
1. Energy flow: Energy flows through various trophic levels in an ecosystem. It starts with the producers (autotrophs), which convert solar energy into chemical energy through photosynthesis.
2. Unidirectional: The flow of energy is unidirectional, meaning it moves from one trophic level to another and does not return to the previous levels. Once energy is transferred from one level to the next, it is used for various metabolic processes or lost as heat.
3. Higher trophic levels: As energy flows through the trophic levels, it is transferred from producers to primary consumers (herbivores), then to secondary consumers (carnivores), and so on. Each level feeds on the previous level, and energy is transferred along the food chain.
4. No return to lower trophic levels: Once energy is consumed by higher trophic levels, it is not returned to the lower trophic levels. The energy is used for growth, reproduction, and other metabolic activities of the organisms at each level. Some energy is also lost as heat in the process.
5. Energy loss: With each transfer of energy between trophic levels, there is a loss of energy. This loss occurs due to inefficient energy transfer, metabolic processes, and heat dissipation. As a result, the amount of energy available decreases with each level.
6. Energy input: The primary source of energy in ecosystems is the sun. The energy input from the sun is captured by autotrophs through photosynthesis and converted into chemical energy. This energy is then passed on to the rest of the food chain.
Therefore, the correct answer is option C: Energy which passes to the higher trophic levels doesn't come back to lower trophic levels.

Maximum concentration of chemicals in the human body

• Bioaccumulation: Chemicals tend to accumulate in living organisms through the food chain, a process known as bioaccumulation.


• Human Consumption: Humans are at the top of the food chain and consume various organisms that may contain accumulated chemicals.


• Higher Trophic Levels: As humans are at higher trophic levels, they tend to accumulate more chemicals compared to organisms at lower trophic levels.


• Longevity: Humans have longer lifespans compared to other organisms, allowing for the accumulation of chemicals over time.


• Biomagnification: Chemicals can also biomagnify in the human body, leading to higher concentrations as they move up the food chain.

Elasmobranchii and Adult Amphibians live in sea water which is hypertonic to them. They need to conserve water thus excrete urea. The urea also acts as Osmoregulator for Adults  Amphibians and Elasmobranchii. To maintain their water balance, Elasmobranchii and adult amphibians drink large quantities of sea water, retaining most of the water and excreting the salt. 

Uric acid passes through the liver, and enters your blood stream. Most of it is excreted in your urine, or passes through your intestines to regulate " Normal" Levels. 

Auxins and gibberellins help promote plant growth, particularly in stem elongation. Cytokinins promote cell division and are produced in growing areas of plants. Abscisic acid plays a role in cell dormancy and is involved in the opening and closing of the stomata on leaves. Finally, ethylene is a gas that is produced by ripening fruits.

 Movement in a sensitive plant 

(i) It occurs in response to an external stimulus like touch and shock.

(ii) Plant cells change shape by changing the amount of water.

(iii) No nerves are involved.

(iv) There is no specialized tissue in plants for conduction of information.

(v) Plant cells do not have specialized proteins.

Route taken by sperm after being deposited into the vagina:

• Vagina: The sperm enters the female reproductive system through the vagina.


• Cervix: From the vagina, the sperm travels through the cervix, which is the lower part of the uterus.


• Uterus: Next, the sperm moves into the uterus, the organ where fetal development occurs during pregnancy.


• Oviduct (Fallopian tube): Finally, the sperm reaches the oviduct, also known as the fallopian tube, where fertilization of the egg typically occurs.

Therefore, the correct route taken by sperm after being deposited into the vagina is: Vagina → Cervix → Uterus → Oviduct.

Flowers are not found in lower plants. Plant like papaya have unisexual flowers. 

Explanation:

• Menopause: Menopause is the physiological cessation of menstrual cycles and reproductive ability in females. It typically occurs in women in their late 40s or early 50s, marking the end of the reproductive phase of a woman's life.


• Loss of Ovarian Function: During menopause, the ovaries stop releasing eggs and producing the hormones estrogen and progesterone, which are essential for menstruation and fertility.


• Symptoms: Menopause is characterized by symptoms such as hot flashes, night sweats, mood swings, and changes in libido.


• Permanent Infertility: Once a woman reaches menopause, she is no longer able to conceive naturally as her body no longer produces eggs for fertilization.


• End of Reproductive Years: Menopause marks the end of a woman's reproductive years and signifies the transition to a new phase in her life.

Cellular Respiration and Photosynthesis are almost opposite processes because photosynthesis removes carbon dioxide from the atmosphere while cellular respiration puts back carbon dioxide.

For the experiment where CO₂  is given out during respiration, KOH solution are taken in a test tube and placed kn the conical flask KOH absorbs carbon dioxide and prevents it from being utilized by the plant for the process of photosynthesis.

The highest rate of respiration are found in the actively growing root and stem tips, cambium and embryos of germinating seeds and lowest rates in dormant seeds or spores. As, the growing tips are generally rich in meristematic tissues the rate of respiration is also high.

Biodegradable Materials

• Paper: Paper is derived from plant fibers and is one of the most common biodegradable materials. It decomposes naturally over time when exposed to the environment.

Non-biodegradable Materials

• Plastic: Plastic is a synthetic material that is not easily broken down by natural processes. It can persist in the environment for hundreds of years.


• Polythene: Polythene, also known as polyethylene, is a type of plastic that is non-biodegradable.


• Aluminium foil: Aluminium foil is a metal material that is not biodegradable. It does not decompose naturally and can take a long time to break down.

Therefore, the only biodegradable material among the given options is paper.

Montreal Protocol Effective Date
The Montreal Protocol, an international environmental treaty designed to protect the ozone layer, became effective in 1989. The protocol was adopted on September 16, 1987, and entered into force on January 1, 1989. It has since been ratified by almost all countries around the world.
Details:
Here are some key points about the effective date of the Montreal Protocol:

Adoption: The Montreal Protocol was adopted on September 16, 1987, during a conference held in Montreal, Canada.

Effective Date: The protocol became effective on January 1, 1989, marking the official start of its implementation.

Objective: The primary objective of the Montreal Protocol is to phase out the production and use of substances that deplete the ozone layer, such as chlorofluorocarbons (CFCs) and halons.

Success: The Montreal Protocol is considered one of the most successful international environmental agreements. It has led to a significant reduction in the production and consumption of ozone-depleting substances globally.

Amendments: Over the years, the protocol has been amended several times to strengthen its provisions and address emerging ozone-depleting substances. These amendments include the London Amendment (1990), Copenhagen Amendment (1992), and Beijing Amendment (1999).

The Montreal Protocol serves as a crucial framework for international cooperation in protecting the ozone layer and has played a significant role in preventing further depletion.

Effects of Ozone Depletion:
There are several effects of ozone depletion on Earth's environment and climate. These include:
1. Increased Ultraviolet (UV) Radiation:
- Ozone depletion leads to an increase in the amount of UV radiation reaching the Earth's surface.
- This is because ozone molecules in the stratosphere absorb and block a significant portion of the UV radiation from the sun.
- With the depletion of ozone, more UV radiation penetrates the atmosphere, leading to potential harmful effects on human health and ecosystems.
2. Negative Health Effects:
- Increased UV radiation can have detrimental effects on human health, such as an increased risk of skin cancer, cataracts, and weakened immune system.
- UV radiation can also damage marine life, including coral reefs, phytoplankton, and other aquatic organisms.
3. Impact on Ecosystems:
- Ozone depletion can have severe consequences for ecosystems and biodiversity.
- UV radiation can inhibit photosynthesis and reduce plant growth, affecting the entire food chain.
- It can also harm plankton, which are vital for marine ecosystems and serve as a primary food source for many marine organisms.
4. Climate Change:
- While ozone depletion itself does not directly cause global warming, it can indirectly contribute to climate change.
- Ozone depletion affects atmospheric circulation patterns, leading to changes in wind patterns, temperature distribution, and precipitation.
- These changes in climate patterns can have subsequent impacts on weather systems and regional climates.
In conclusion, ozone depletion primarily results in an increase in UV radiation reaching the Earth's surface, which has negative consequences for human health, ecosystems, and climate.

Correct option is B)

• The plant cell can do respiration and photosynthesis.
• The plants get energy through the process of respiration in which glucose food breaks down in the presence of oxygen to form carbon dioxide and water with the release of energy.
• In plants, photosynthesis takes place in the cell organelle called chloroplast. A plant cell cannot breathe because in a plant body lungs are absent.

So the correct answer is 'Respiration and photosynthesis'.

Respiration is constitutive process that occurs in all tissues. Unlike photosynthesis that can happen only in the presence of sunlight, respiration in plant occurs all time. So, the answer is - both light and dark.

Fossils are dead remains of animals and plants from the remote past.

Fossils are formed when dead organisms are not completely decomposed. The organisms may get trapped in resins of trees, lava of volcanoes or hot mud, which when hardened retains the animal’s parts thus forming fossils.

Trilobite, any member of a group of extinct fossil arthropods easily recognized by their distinctive three-lobed, three-segmented form. For the animal to grow, the exoskeleton had to be shed, and shed trilobite exoskeletons, or portions of them, are fossils that are relatively common.