Estudiamos las funciones de relación en las plantas

Hay personas que aún no ven a las plantas como seres vivos capaces de llevar a cabo las tres funciones vitales. Creen que, porque las plantas no tengan sistema nervioso, no son capaces de elaborar respuestas ante los cambios que hay en el ambiente que las rodea, o incluso en su interior. 

En esto consiste precisamente la función de relación en las plantas, en la capacidad que tienen de responder ante estímulos; los más importantes son la luz, la temperatura, la gravedad y la humedad. Y las respuestas más frecuentes son los movimientos o los cambios estacionales. 

Los movimientos pueden ser rápidos, de corta duración; se denominan nastias. Como os decía en la entrada anterior, pueden ser movimientos apreciables frente a la luz como los que presentan los girasoles, cuyas flores, como sabéis, van cambiando de posición a lo largo del día. Y alguno de vosotros en clase me ha preguntado en alguna ocasión por las plantas carnívoras, esas que se cierran cuando atraen a un insecto y se deposita sobre ellas.

En otros casos los movimientos son lentos, aunque permanentes. Es el caso del crecimiento de las plantas hacia la luz o el crecimiento de las raíces hacia zonas húmedas o buscando la profundidad.

Pero también las plantas con capaces de medir el tiempo. ¿Quién les dice que deben florecer en primavera a la mayoría de ellas? ¿Y a otras que lo deben hacer en otoño? Pues la duración de los días; hay plantas que necesitan un número elevado de horas de luz, mientras que con otras sucede lo contrario.

Pues bien ¿podemos, en estos días en los que debemos estar en nuestras casa, estudiar las funciones de relación? Pues claro. Pero ante todo, ¿cómo lleváis el experimento que os propuse? Si todo va bien, ya deben haber germinado vuestras semillas y habréis comprobado como las raicillas se dirigen hacia abajo (geotropismo positivo, es como si la Tierra tirara de ellas) y los tallitos hacia arriba (geotropismo negativa, crecen en contra de la gravedad).

Pero podemos preparar un nuevo experimento para ver el papel de la luz en el crecimiento de las plantas. Ahora vamos a cultivar lentejas; muchos de vosotros ya sabéis el procedimiento pues lo habéis desarrollado en el proyecto de biología. Tomáis un recipiente a reciclar, añadís papel de cocina y sembráis unas lentejas. Lo regáis y dejáis que germinen. A continuación introducís vuestras pequeñas macetas en una caja a la que le habéis abierto un agujero en un lateral. Dejáis que sigan creciendo y comentamos los resultados. Como os decía, unas fotos de nuestros resultados serán bienvenidas a este blog, por supuesto diciendo quiénes las habéis hecho. 

Otro experimento. Si ya habéis conseguido que vuestras plantas de la semana pasada hayan germinado y veis cómo van creciendo, tumbad el bote con mucho cuidado de que no se derrame agua y dejad que la planta siga creciendo. ¿Habrá algún cambio dentro de unos días?

Y hay más cosas que podéis hacer. ¿Tenéis en vuestras casas macetas de interior? Observad estas plantas y ver si su crecimiento se dirige hacia alguna ventana. Comentad estas ideas con vuestros padres a ver si ellos se han dado cuenta de esto.

Y ya sabéis, espero vuestros resultados como comentarios en este blog. Y también vuestras propuestas de experimentos. Os recuerdo que para cualquier consulta o para que me enviéis las actividades mi correo electrónico es: aquesada@ieszaidinvergeles.org. 

Cuidaos mucho.

Plants and interaction

Wikipedia

You know that interaction is a vital function that allows living beings to respond to changes in the environment around them or within their own organism. People think that plants are different to animals and they are not able to interact with the environment. What a big mistake!

Plants react to different stimuli. The most important ones are light, temperature, gravity and humidity. And the most common reactions of plants are movements and seasonal changes. There are two kind of movements: nastic movements and tropisms.

Nastic movements are rapid movements of some parts of the plant. Photonasty is a response to light, for example in sunflowers. Thigmonasty is a response to contact. You can see this movement when you touch a plant named Mimosa pudica. And what happens when a carnivorous plant traps an insect?

Tropisms are slow and irreversible plant responses in which plants direct their growth towards a stimulus, if positive tropism, or away from in, in case of negative tropism. For example, phototropism is a response to light; hydrotropism, to the presence of water.

J.hagelüken. Wikipedia

Have you ever wondered why most plants flower bloom in spring? How do they know when it is time to produce flowers and reproduce? Plants react to seasonal changes and they are able to notice the length of days or nights. In spring, days last lot of hours. Plants modify some of their vital processes as a responde to changes in the environment, like temperature or light.

And now, some questions:

1. What are the most important stimuli to plants?

2. What are the difference between tropisms and nastic movements?

3. What kind of reaction is produced in a a plant when the stem of a grass grows towards the light in order to avoid the shade of a tree?

4. Why do the roots of plants grow to areas where there is water in the ground?

5. Give an example of a nastic movement and a seasonal change.

Estudiamos el desarrollo de las plantas

En estos días en los que tenemos que permanecer en nuestras casas y hacer de ellas nuestras aulas os voy a proponer un experimento sencillo -este en castellano, aunque podéis hacer vuestros comentarios en inglés- para que podamos comprobar cómo se desarrollan las plantas. ¡Vamos a sembrar semillas!
Podemos utilizar cualquiera de las semillas que tenemos en casa, pero yo os recomiendo las judías (alubias). Son más grandes que otras semillas lo que nos permitirá ver mejor los procesos que van a tener lugar.
Para llevar a cabo nuestro experimento necesitamos un bote de cristal transparente de esos que ya no necesitamos y que reciclaremos para este experimento, varias hojas de papel de cocina, nuestras semillas y agua.
Enrollaremos suavemente varias hojas de papel de cocina haciendo un cilindro que introduciremos en nuestro bote de vidrio. Procuraremos que haga suficiente presión como para sujetar las semillas a media altura, sin que se caigan al fondo del bote.

Añadiremos agua a nuestro bote hasta que alcance una altura de un par de centímetros. El agua ascenderá por capilaridad por el papel y nuestras judías recibirán la humedad necesaria para germinar. Debemos cuidar que siempre haya una cantidad suficiente de agua para que no se seque el papel.
Iremos observando nuestras plantas a medida que pasan los días y describiremos cómo se lleva a cabo el proceso. Podemos ir tomando imágenes para describir gráficamente qué sucede. Una vez que la planta tenga el tamaño apropiado podemos transplantarla a una maceta con tierra.
Y esto que os he contado es lo básico. Si hacemos esto veremos cómo germina una semilla y cómo crecen las plantas. Pero podemos experimentar y así hacemos ciencia. Os planteo algunas preguntas y vosotros diseñáis los experimentos y cómo llevarlos a cabo:
¿Tardan las semillas de los distintas plantas el mismo tiempo en germinar?
¿Afecta la temperatura a la germinación de las semillas?
¿Germinan las semillas mejor en presencia de la luz o en oscuridad?
¿Afectarán los productos que tenemos en casa a la germinación y al crecimiento de las semillas?
Seguro que a vosotros se os ocurre algún experimento más.
Y bien, puesto que uno de los aspectos más importantes de la ciencia es compartir los resultados vamos a ir comentando cómo transcurren nuestros experimentos en nuestro blog. En primer lugar os agradecería que comentarais si vais a hacer alguno de los experimentos que proponemos o que vosotros proponéis. En segundo lugar quiero que vayáis valorando qué resultados vais viendo. Y vosotros mismos, o con la ayuda de vuestros padres o vuestras madres, podéis ir tomando fotos y enviármelas comentadas a esta dirección de correo: aquesada@ieszaidinvergeles.org. Las mejores las iré publicando en el blog. Y otra cosa importante, también podemos comentar los resultados de nuestros compañeros y compañeras.
Ah! Y tendréis Vergeles por los resultados de vuestros experimentos.

Plants and nutrition

I am sure that you know what a plant is. You know that they are living organisms, you can see them every where and most of them are green. Plants are members of the kingdom plantae and they include trees, flowers, grass and more. 

Plant cells are composed of rigid cell walls made of cellulose. They have a nucleus, large vacuoles filled with water, ribosomes, mitochondria and chloroplasts.

Plant cell. Wikipedia.

The three basic parts of most plants are the leaf, the stem  and the root. 

The leaf is an organ that is specialized for photosynthesis. By this process plants make their own food. It takes place in the cell chloroplasts thanks to the light energy from the Sun. Water and carbon dioxide are transformed into sugars and oxygen is released as a waste. So, leaves are mainly flat and thin in order to catch as much sunlight as possible. 

The stem is the main structure that supports leaves and flowers. Stems have vascular tissues that move water, salts and food around the plant. Xylem sap travels from the roots to the green parts of the plant and the phloem sap travels from the green parts to all the plant's cells. Some plants, like potatoes, store food in their stems.

Roots fix the plant in the ground and enables it to absorb water and mineral salts. Some plants store foods in their roots.

Plants respire too, like animals. Respiration takes place in the mitochondria. In order to carry out this process, plants absorb oxygen and get energy from sugars obtained during photosynthesis. Water and carbon dioxide are produced.

And what happen with waste products? Plants have no specialised organs for excretion. This function is carried out by the plant's entire surface. The waste products are oxygen, water and other substances like latex.

And now some activities. Please answer them as comments.

1. How do you say in Spanish: leaf, stem, root, sugar, waste, sunlight, sap? 

2. What organelles can you find in a plant cell?

3. In which organelles does photosynthesis take place?

4. What is the name of the mixture of water and mineral salts?

5. Where does the distribution of substances in plants take place?

6. Which organelles are responsible for respiration in plants?

The golden record

Voyagers

Voyager 1 and 2 are two spacecraft that were launched in 1977. Both of them explored Jupiter and Saturn. Voyager 2 went on to explore Uranus and Neptune but Voyager 1 went off in a different direction. They sent us fantastic pictures from the Solar System. Now, more than 40 years old, both of them are still going and going and they have left the Solar System.

Voyager 1 and 2 contain a curious message aboard. It is a kind of time capsule, intended to communicate a story of our world to extraterrestrials. It is a golden disk with recorded sounds and images selected to show the diversity of life and culture on Earth to aliens, in case they exist and find out one of these spacecrafs.

All the contents were selected by Carl Sagan, a very famous astronomer, and his team. In the golden record there are 115 pictures from Earth and a variety of natural sounds like those made by wind and thunder, birds, whales and other animals. The added musical selections from different cultures and ages and spoken greetings from Earth people. 

Creating our own golden record

But everything was made more than forty years ago. Now we have new pictures from Earth, it is easy to look for them on Internet, and there are thousands of new songs to send to aliens. So, we are going to prepare a new golden disk, with new images, new songs and new greetings for new Voyagers. 

 You will have to choose one  picture from our world and justify your choice. You will select a song in English and sing a short part of it. Think about the best song you will send to extraterrestrial people. And finaly, write a greeting for them.  We will select the five best ones to include in our particular spacecraft. 

Terraforming Mars

Mars is the fourth planet in our solar system.  Its name comes from the Roman god of war.  Mars is also known as  the Red Planet because of its color, due to the presence  of rusty iron in the ground. It is a terrestrial planet, small and rocky. The planet gravity is 38% of Earth’s. Mars has big volcanoes; Olympus Mons is the highest volcano in the Solar System. But all of them are dead.  It also has lot of impact craters. Mars has two moons: Phobos and Deimos.

Mars (https://mars.nasa.gov/system/resources/detail_files/7808_global-color-views-mars-PIA00407-full2.jpg)

Mars has a thin atmosphere;  it is made of carbón dioxide, nitrogen and argon. It hasn’t got oxygen. So, human beings cannot breath there. The temperature is very cold; it ranges from -125 ºC to 15 ºC. In the past, it was warmer. Huge dust storms occur on Mars.

Mars had lots of liquid water in the past. Now water exists as ice in the poles and, perhaps, beneath the surface. On some martian places, there is evidence of liquid salty water in the ground, but these salts may be toxic for living beings. 

One day on Mars lasts 24.6 hours. It is just a little longer than a day on Earth. One year on Mars is 687 Earth days. It is almost twice as long as one year on Earth. Like our planet, Mars has seasons.

Scientists want to know if Mars may have had living things in the past. They also want to know if Mars could support life now or in the future. Some of them think that colonizing the Red Planet is essential for the future of humanity.

But if we want to live in Mars, we have to make the planet habitable. We have to terraform Mars. Terraforming is the use of technology to transform an inhospitable planet into a habitable one, with the Earth qualities needed to sustain human life. 

Terraforming Mars (Wikipedia)

To terraform Mars, scientists would have to change the atmosphere composition, to raise the level of greenhouse gasses in order to increase temperature, to raise the level of oxygen to breathe and to get liquid water. Can you help scientists to change Mars and make it habitable for human beings? What do you suggest?

References
https://spaceplace.nasa.gov/all-about-mars/en/
https://easyscienceforkids.com/all-about-mars/
https://schooledbyscience.com/terraform-mars-possible/

3D Mars: making anaglyphs

How does 3D work? 

3D (three-dimensional) means that an object has width, height, and depth. On the contrary, a 2D object does not have depth and thus is flat, just like a sheet of paper.
Because our eyes are spaced apart, each eye sees the same 2D view, but from a slightly different perspective. The brain puts the 2D image from each eye together, giving us a 3D view of the world. That is, we can perceive depth.

Making anaglyphs

We can create a 3D image by superimposing two 2D images. It is called anaglyph, and this picture simulate the way our eyes work. Making an anaglyph is so simple that anybody with a camera, computer equipped with photo-editing software, and a pair of tinted glasses can make their own 3-D pictures of Mars, family members, pets…
In an anaglyph, the same 2D picture is overlapped, but spaced slightly apart. One of the overlapped images is colored cyan, and one red. We can achieve this by using two cameras side by side, or only one and moving its position horizontally. With the help of the software Anaglyph Maker we will get our 3D pictures.
When we look an anaglyph with 3D glasses, the lenses only allow the red image to enter the left eye and the cyan image to enter the right eye. The visual cortex of our brain fuses the two images, and we perceive the image in 3D.

Making 3D glasses

Take the template, cut out the glasses, including the holes for the eyes. Cut one cyan-color cellophane and one red-color cellophane. The two pieces will cover the eyeholes in the glasses. Glue the cellophane on the inside of the glasses. Place the red cellphane on the left eye and the cyan cellophane on the right eye (left and right when the glasses are on our face).

XXII Solar Week: The Sundial Project

If you want to know what time it is, you probably watch at your wristwatch or mobile phone. But imagine that you live some centuries ago... Sundials are the oldests known instrument for telling the time. In fact, the earliest known sundial was made by Egyptians about 3.500 BC. As the Sun moves across the sky, the shadows objects cast move too. And people use this movement to know the time.

There are two parts in a sundial. One of them is called a gnomon; normally a stick that cast a shadow. The other one is a flat surface with marks, one for each hour of the day, where the shadow is projected. This is the dial plate. Those marks are usually numbered lines, the hour lines, that show the hours of the day. As the day passes, the gnomon' shadow moves around the dial; the shadow falls on a new line every hour.

Our Science Week is coming; and as every year, we are going to work about sundials. We are going to learn about these instruments, how they work, different types of sundials. And the most important... you are going to build your own sundial. Don't worry; it's very easy. Here you have some sundials made by students last year.

But, in my opinion, it is important to know about sundials in Granada too. How many sundials are there in Granada? Where are they? What kind of sundial is every one of them? Answer these questions as comments. Please, and if you can, take photos of those sundials. Send them to me and I will include your images in our blog.

And now, a very difficult question: where is the sundial of the picture below?

Recursos:

Construcción de relojes solares. Incluye la descripción de los principales tipos de relojes de sol así como plantillas de los cuadrantes solares para relojes orientados.

Algunos modelos de relojes solares.
Relojes solares otras semanas de la ciencia del IES Zaidín Vergeles.
La sombra del tiempo. Relojes solares del IES Zaidín Vergeles en el diario Granada Hoy.
Son muchas las páginas web dedicadas a la gnomónica y a la construcción de relojes solares. Algunas de las más representativas son:
Relojes de Sol de Mallorca.
Reloj andalusí. Web andaluza de relojes solares.
Relojes de Sol de la provincia de Málaga.
Asociación Amigos de los relojes de Sol.
North America Sundials Society.
Sundials on the Internet.

Growing microorganisms at our laboratory

In these days we are studying microorganisms in our classes. Bacteria are the most abundant living beings all over the planet and we can find them everywhere. Today we are going to confirm it. At our laboratory, we have prepared some Petri dishes with culture medium, and we have put different objects over it: our fingers, different plant leaves, our keys, ear rings... We have even sung a song to a Petri dish. Tomorrow we will see our results. If bacteria are everywhere, we will expect that our bacteria grow. In this case we will see lot of colonies of different sizes, colors and shapes. Perhaps we will have some fungi. I would like to know your opinion about our experiments. I know that some of you want to repeat these experiments at home. I have some Petri dishes for the best comments. 

Journey to the center of the Earth: Making crystals

The lava, porous in places, was covered with little round bulbs; crystals of opaque quartz, decorated with clear drops of glass, hung from the vaulted ceiling like chandeliers, and seemed to light up as we passed. It was as if the spirits of the underground were lighting up their palace to welcome their guests from the Earth.

‘It’s magnificent!’ I shouted in spite of myself. ‘What a sight, Uncle! Look at the colours in the lava which go from reddish-brown to bright yellow absolutely continuously. And these crystals that look like luminous globes!’

‘So you admire all that, my boy? You will see lots more, I hope.’

Jules Verne: Journey to the centre of the Earth

Crystals are a special kind of solid material where the molecules fit together in a repeating pattern. This pattern causes the material to form all sorts of unique shapes.

Crystals can have very flat surfaces called facets. They can form geometric shapes such as triangles, rectangles, and squares. The shapes are a direct result of the type of molecules and atoms that make up the crystal. Smaller crystals and larger crystals that were formed of the same molecules and in the same method should have similar shapes.

The process of crystal forming is called crystallization. Crystals often form in nature when liquids cool and start to harden. Certain molecules in the liquid gather together as they attempt to become stable. They do this in a uniform and repeating pattern that forms the crystal.

In nature, crystals can form when liquid rock, called magma, cools. If it cools slowly, then crystals may form. Many valuable crystals such as diamonds, rubies, and emeralds form this way. Another way crystals form is when water evaporates from a mixture. Salt crystals often form as salt water evaporates.

Can we make crystals? Of course. A good example is when saltwater is left to dry. The moisture will slowly evaporate and the only thing that is left is the salt. Salt appears in crystallized form.

Another example is to grow ammonium phosfate or copper sulphate crystals. Both of them are safe chemicals for producing a mass of crystals quickly. The first one is a white powder that yields clear crystals; the second one is a bluish power that forms beautiful dark blue crystals.

To get the crystals we have to stir salts into boiling water until the powder is completely dissolved. Put the solution into a container in a location where it will not be disturbed. If we want to get large crystals, let's try to cool the solution slowly from very hot down to room temperature. If we want big crystals we can take a small single crystal and place it in a new growing solution.

Good luck!!

And here, our first results. Beautiful crystals!