Notes, abstracts, papers, exams and problems of Biology

6. Fill in the gaps with words from the box

1. Viruses are a type of microorganisms which are not affected by antibiotics

2. We couldn’t           the experiment because the machine didn’t work come up 

3. Any national government has been able to       with effective measures to lower COVID expansion.

4. The results are inconclusive and that’s why scientists haven’t been able to find a cure yet

5. These tomatoes have been genetically modified 

6. Remember to turn off all the machinery before leaving the laboratory

7. The samples need to be poured into test tubes after being processed

8. Some women receive hormone treatment to control irregular periods

Vertebrate animals belong to the Animal Kingdom and have the following characteristics:

• They have an internal skeleton that allows movement, protects the organs, and gives support to their body.
• They have blood to carry the nutrients and waste products throughout the body.
• They have articulated limbs (fins, wings, or legs).

We are going to study the vertebrates' groups:

1. Fish

• Aquatic (they have a fusiform body, thinner in the tips, and fins). They breathe through gills.
• Poikilothermic (they cannot maintain constant body temperature).
• They have a lateral line (a line that crosses their body that is able to detect vibrations in the water).
• They have external fertilization: gametes join in the environment, outside of the female's body.
• They can be oviparous

Ecosystem

An ecosystem is a community of plants and animals (living things) that interact with each other and their natural surroundings, including non-living things such as rocks, water, and air. Each ecosystem is sustained by a flow of energy through it and the recycling of nutrients within it.

Community

When plants and animals live together, they form a community.

Photosynthesis

Photosynthesis is the process in which plants absorb CO₂ from the air and convert it into sugar using the sun's energy.

Biomes

Biomes are large ecosystems at the global scale where the climate and vegetation are uniform.

Xerophytic Plants

Xerophytes are plants that have adapted by altering their physical structure to survive in harsh climates. These plants exhibit several... Continue reading "Introduction to Ecosystems and Ecology" »

The Interaction Function

The interaction function enables people to perceive changes and stimuli that occur both inside their bodies and their environment, to interpret or process them and generate coordinated responses in order to survive.

1.1 Perceiving Stimuli

The interaction function can be divided into 3 stages: perception of stimuli, processing of the information and generation of responses.

A stimulus is a physical or chemical change that takes place outside or inside the body and triggers a response in it.

Our bodies contain specialist cells, called receptors, which perceive stimuli and send the information they detect to the coordination centres.

Types of Receptors

• Internal receptors perceive changes inside the body, such as a rise in blood

Muscle spindles stimulate stretch, while Golgi tendon organs stimulate muscle contraction. Cerebellar tremor is characterized by low frequency. Motor pathways begin in the cerebral cortex and brainstem. Lower spinal cord motoneurons innervate skeletal muscles, including extrafusal and intrafusal fibers. Stimulation of muscle spindles or Golgi tendon organs is accomplished through the reticulospinal tract.

Muscle Tone and Movement Disorders

• Hypotonia: Decreased muscle tone
• Dyskinesia: Atypical, unconscious muscle movement
• Hypertonia: Increased muscle tone
• Spasticity: Hyper-contraction of muscles
• Akinesia: Atypical unconscious posture

Cortical Control of Movement

Layer V contains pyramidal neurons. The primary motor cortex contains smaller and fewer... Continue reading "Motor Control: Pathways, Neurons, and Muscle Function" »

Replication

AAGGCCTAGC-TTCCGGATCG

Transcription

AAGGCCTAGC

Translation

How to Read the RNAm to Make Proteins After the Transcribing DNA as RNAm

It exists from the nucleus to the cytoplasm. There, ribosomes are waiting for the RNAm, and the two subunits look for the first codon AUG. The RNAm is read by triplets. All the possible combinations of codons and its corresponding amino acids are called genetic code. Mutation is the alteration of the DNA sequence that can be transmitted to the offspring (if it occurs in gametes).

Addition:

A nucleotide is added

Deletion:

A nucleotide is removed

Substitution:

A nucleotide is changed

1. Fungi obtain nutrients through absorption.
2. The body of most fungi consists of threadlike hyphae, which form a network called a mycelium.
3. Some fungal species live in plants and can kill herbivores that feed on the plant. What type of relationship does this fungus have with its host? Mutualistic
4. What sexual processes in fungi generate genetic variation? Karyogamy and meiosis
5. Almost all of the members of this phylum form arbuscular mycorrhizae in a mutualistic partnership with plants. Glomeromycota
6. From the human perspective, which of the following kinds of fungi would be considered the least useful or beneficial? Rusts
7. Which of the following best describes the physical relationship of the partners involved in lichens? Photosynthetic cells are

Protein Synthesis: From DNA to Protein

1. Transcription: Copying the Genetic Message

Transcription is the process of copying part of the genetic message from DNA to RNA so that it can be used to synthesize a specific protein.

Stages of Transcription:

• The double helix of DNA unwinds.
• Complementary nucleotides position themselves opposite one of the two strands.
• Only one of the DNA strands is copied.
• An RNA strand is produced with a sequence of bases that is complementary to the DNA bases.

2. Translation: Building the Protein

Stages of Translation:

• The message copied as RNA is identical to the message in the DNA (except it contains uracil instead of thymine).
• This RNA, known as messenger RNA (mRNA), is a single-chain molecule that can leave the nucleus.

The Pancreas

Long, greyish-white organ behind and underneath the stomach. Functions: Produces hormones (insulin & glucagon) that regulate the amount of glucose in the bloodstream. Secretes pancreatic juice which contains digestive enzymes & sodium bicarbonate.

How Digestion Works

Most digestive processes take place in the small intestine. Digestion produces nutrients that cells need:

• Monosaccharides (simple sugars): obtained from complex carbohydrates.
• Glycerol & fatty acids: obtained from fats.
• Amino acids: obtained from proteins.

Nutrient Absorption

Nutrients pass from the small intestine into the bloodstream through absorption and then are delivered to cells by the blood. The inside wall of the small intestine is covered in folds that... Continue reading "Understanding the Pancreas and Respiratory System" »