Biology Practice Flashcards (Iraq Scientific Secondary 5)

A comprehensive set of practice flashcards covering nutrition, respiration, excretion, movement, transport, nervous coordination, and hormones for Iraqi 5th Scientific Secondary students.

What are autotrophs?

Organisms which can produce their own food, most of which are photosynthetic and contain chlorophyll.

What is the difference between phagocytosis and pinocytosis?

Phagocytosis (swallowing) is the taking of large solid particles into the cytoplasm, while pinocytosis (cell drinking) involves taking in liquids.

What is active transport?

Taking of necessary materials from a low concentrated medium to a high concentrated medium by using energy ($ATP$).

Where do light and dark reactions of photosynthesis occur in the chloroplast?

Light reactions occur in the thylakoid membranes, and dark reactions (the Calvin cycle) occur in the stroma.

What is the chemical formula for photosynthesis?

$$6 CO_2 + 12 H_2O \xrightarrow{\text{Light energy}} C_6H_{12}O_{6} + 6 O_2 + 6 H_2O$$

Which scientist discovered the light and dark reactions of photosynthesis?

Scientist Blackman.

What is chemosynthesis?

The process where some bacteria produce organic materials by oxidizing inorganic materials (like ammonia or hydrogen sulfide) without sunlight.

Which bacterium converts ammonia ($NH_3$) into nitrate ($NO_2$)?

Nitrosomonas.

What is the function of the enzyme ptyalin?

It is involved in the digestion of complex carbohydrates like starch and is found in the mouth of animals like snails, mammals, and humans.

What is the difference between intracellular and extracellular digestion?

Intracellular digestion occurs inside food vacuoles within the cell, whereas extracellular digestion occurs outside the cell in a lumen, gastric cavity, or digestive organ.

What is peristaltic movement?

The wave-like contraction and relaxation of muscles in the wall of the digestive tract that moves food.

What are the functions of the liver mentioned in the text?

Detoxification of blood, storage of vitamins ($A$, $B_{12}$, $E$, $D$) and iron, production of albumin and fibrinogen, converting ammonia to urea, and producing bile.

What is cellular respiration?

The process where glucose is activated and broken down to release energy ($ATP$), water ($H_2O$), and carbon dioxide ($CO_2$).

What are the four phases of aerobic cellular respiration?

1. Glycolysis (cytoplasm); 2. Pyruvate oxidation (mitochondria); 3. Citric acid cycle or Kreb's cycle (mitochondria); 4. Electron transport system (ETS).

What is the difference between external and internal respiration?

External respiration is gas exchange between the blood and the environment; internal respiration is gas exchange between the blood and body cells.

How do woody plants maintain gas exchange?

Through lenticels, which replace stomata as the plant matures.

What are the respiratory organs of terrestrial arthropods like insects?

Tracheae, which are a system of pipes that open to the exterior via spiracles.

What is cutaneous respiration?

Gas exchange that occurs through the skin, common in amphibians and some fishes.

What is the function of air sacs in birds?

They increase oxygen storage capacity and facilitate the bird's ability to fly by filling the body cavity/bones with air.

Define guttation.

The elimination of excess water from a plant in the form of drops through hydathodes.

What are flame cells?

Excretory structures in planaria that use ciliary movement to excrete waste and regulate water balance.

What are the three types of vertebrate kidneys?

Pronephros (primitive/embryonic), Mesonephros (adult fish/amphibia), and Metanephros (adult reptiles/birds/mammals).

What is the functional unit of the human kidney?

The nephron, which consists of Bowman's capsule, the glomerulus, and the convoluted tubules.

What is the difference between phototropism and geotropism?

Phototropism is a response to light (stem is positive, root is negative); geotropism is a response to gravity (root is positive, stem is negative).

What are the three types of muscle tissue in animals?

Skeletal (voluntary/striated), Smooth (involuntary/non-striated), and Cardiac (involuntary/striated).

How does an earthworm move?

Using a hydrostatic skeleton, where circular muscles shrink/expand the body and long muscles make it longer/shorter, aided by chitinous stingers.

Define transpiration.

The process by which excess water is excreted from plant stomata as vapor.

What are the cohesion and adhesion theories in plant transport?

Cohesion is the attraction between like molecules (water to water); adhesion is the attraction between unlike molecules (water to xylem vessel walls).

What is the difference between an open and a closed circulatory system?

In an open system, heart-pumped fluid (hemolymph) fills body cavities; in a closed system, blood is contained within blood vessels.

Describe the heart structure of a fish.

A two-chambered heart composed of one atrium and one ventricle, containing only deoxygenated blood.

What is a foramen panizza?

A small orifice in the ventricle of a crocodile's heart that allows some mixing of blood.

What is the 'first pass effect' in human circulation?

When drugs absorbed via the digestive tract are metabolized by the liver before reaching general circulation.

Why do mammalian erythrocytes lack a nucleus at maturity?

To transport oxygen and carbon dioxide more efficiently (they also lack mitochondria, Golgi apparatus, and endoplasmic reticulum).

What is a neuron?

A specialized cell of the nervous system used for impulse transmission, consisting of dendrites, a cell body, and an axon.

What is the 'all-or-none law' regarding nerve impulses?

An impulse is generated only if the stimulus reaches a certain critical threshold level; any voltage below this fails to generate an impulse.

Define the synapse.

The junction where an impulse is transmitted from the axon of one neuron to the dendrites of the next.

What are the three components of the human Central Nervous System ($CNS$)?

The brain and the spinal cord.

What is the difference between the sympathetic and parasympathetic nervous systems?

The sympathetic system accelerates certain organ functions (like heart rate), while the parasympathetic system decelerates them.

What are proprioceptors?

Receptors that sense the degree of muscle contraction and tendon stretch to maintain body posture.

What is the lateral line system in fish?

A system of sense organs (hair cells) used to detect movement and vibration in the surrounding water.

List the five types of plant hormones.

Auxin, cytokinins, gibberellins, abscisic acid ($ABA$), and ethylene.

What is the role of ethylene in plants?

It determines the maturation of fruit and the life span of the plant.

Which gland produces insulin and glucagon?

The pancreas (specifically the Islets of Langerhans).

What are neuro-hormones?

Secretions of the hypothalamus that control the endocrine system via the pituitary gland.

What is the function of the thyroid gland?

It secretes thyroxine which regulates metabolism and calcitonin which reduces blood calcium levels.